Recently I was involved in a discussion about the intended audience of 4E, and what WotC was trying to accomplish with the design. The following point came up:
I suspect the real issue for many people in terms of roleplaying support between 3.5 and 4e is the lack, in 4e, of mechanical definition for non-combat abilities -- craft, profession, perform... and limited multiclassing (making it difficult to define a character with an interesting past reflected in their class levels).
Now, some of these things are simple fact. 4E doesn't have Craft or Profession. This loss takes away an easy hook for character background ("I used to be a bartender, as reflected by my Profession skill."). I've also talked with many people who enjoy the world simulation aspect of Craft - the ability to determine just what their character can accomplish in the week between adventures, and how his work compares to that of the local smiths. Perhaps something will be added in the future, but it's plain and simple fact that it's not there (which I am slightly amused by, since it's somewhat at odds with the statement that 4E is a pen-and-paper MMO... Crafting being an important subsystem of most major MMOs).
Performance isn't a total loss, as there are certain forms of performance that can be represented by other skills. As I mentioned earlier, I ran a skill challenge in which the PCs had to perform an improvised play to gain admittance to a guild enclave. None of them had a Perform skill as such, but they had skills they could justify as being relevant: Bluff for general acting, Diplomacy for that dramatic monologue appealing to the audience, Intimidate for the guy playing the villain, Acrobatics for gymnastics and tumbling, and so on. However, while it's easy enough to say "Bluff is your acting ability", there's no way to represent your skill as a harper. And while a DM might say "You want to be a poet – use your Diplomacy skill for that" presumably not EVERYONE with Diplomacy is a great poet. So certainly, the loss of Craft, Performance, and Profession removes a flavor tool present in 3E.
However, I disagree with the idea that it's mechanically "difficult to define a character with an interesting past" in 4E. It's certainly difficult to do that with CLASS LEVELS, because that's not the mechanic 4E uses for this purpose. Class levels determine your combat abilities, and it's intentionally difficult to dramatically change your combat role. But once you step out of combat, the skill training system makes it easy to develop cross-class skills – and because heroic tier feats have less of an impact on your combat abilities than 3E feats, it's not a major sacrifice to use your feats on noncombat abilities. The amalgamation of skill groups further helps with this. I have a changeling (doppelganger) cleric-thief in one of my games, and while he hasn't actually taken any rogue POWERS, through the use of two feats (Sneak of Shadows to gain Thievery and Skill Training - Stealth) he has gained decent ability in what would have been five skills under 3.5, without any significant sacrifice of his clerical abilities. In 3.5, he'd HAVE to multiclass to get that level of skill, and that would drop his clerical power. He doesn't have the COMBAT power of a rogue - but *out* of combat, he feels like a 3.5 rogue.
But the main point I wanted to address was whether it's possible to "define a character with an interesting past". The changeling cleric is one example. His idea was that while raised in the church, he was faced with corruption in the ranks - and that now, as a pilgrim, he seeks to understand these darker aspects of human nature so that when he returns he will be better equipped to face it. He began with Skill Focus (Stealth), as this was tied to how he'd discovered the corruption to begin with; at second level he took Sneak of Shadows, reflecting his deeper study of these arts. Again, he doesn't FIGHT like a rogue - but his noncombat abilities directly reflect his past and evolving story.
Just to continue to ramble at great, unnecessary length, let me go ahead and present two additional characters. Both are first level human fighters, and both have 18 Strength; I want to develop an interesting backstory, but I'm not going to sacrifice my primary stat to get it.
LUCAS grew up on a farm; he became an adventurer after his village was destroyed by the soldiers of a cruel overlord. He's not terribly bright or well educated, but he's got a good heart, a lot of common sense, and a good sense of people. His experience with animal husbandry has taught him how to heal, though his friends might be disturbed when they hear him talk about birthing foals while patching their wounds. His combat skills come both from his brute strength – built up by his time laboring on the farm – and from time spent hunting with his spear in the woods.
Str 18, Con 14, Dex 13, Int 8, Wis 14, Cha 10
Feats: Skill Focus (Insight), Warrior of the Wild
Skills: Athletics +9, Endurance +7, Heal +7, Insight +10 (racial skill training), Nature +7 (from Warrior of the Wild)
There's lots of other ways I could have gone here. Obviously I could switch that Skill Focus to play to the element of my background I want to be the strongest; I went for Insight because it's going to allow me to contribute to social situations (I'm not intimidating or diplomatic, but my common-sense, folksy insights often help out). If I traded Nature for Perception and Insight for Stealth, I've got more of the spear-hunter – I don't fight like a ranger, but with a +9 Stealth (assuming scale armor), I'm capable of sneaking around alongside ranger or rogue. Now what Lucas DOES lack is Profession (Farmer). However, it's my past as a farmer that justifies my Nature and Heal skills – and it's something that I can roleplay to during skill challenges involving them. And if it actually came to, say, identifying farming equipment, as a DM I'd likely just give this to Lucas for free because it obviously fits his background.
Taking another path, we've got GRIM. He was born in a back alley in the big city, and his sheer strength and force of will was the only reason he survived. He began as a bouncer in a bar, and then became an enforcer for a local crime boss; unfortunately, a feud with a rival gang went against his side, and he's been forced to flee the city and take up a life of adventure. His notable trait is the one he takes is name from – his intimidating demeanor. But he also knows his way around the streets.
Str 18, Con 14, Dex 10, Int 8, Wis 13, Cha 14
Feats: Skill Focus (Intimidate), Skill Focus (Streetwise)
Skills: Athletics +9, Endurance +7, Intimidate +10, Streetwise +10 (racial skill)
Because of the nature of skill challenges, Grim's still going to be useful even if you have a rogue or warlock who's focused on the social skills; since it's not just a single-check resolution, if a challenge calls for Streetwise, the more skilled characters the better.
Now, you could say "You CAN make these characters, but would you? I'd take Con 16 (with the subsequent drop in other scores), Toughness and Weapon Focus." Personally, I'd take either of these characters over the Toughness-Weapon Focus route, both because they have more flavor and because in the campaigns I'm in, the +10 Streetwise will be much more useful than five more hit points. If your DM actually uses skill challenges in a significant role, the +3 bonus from Skill Focus is far more significant than the +1 damage from Weapon Focus. I'm playing a paladin in one of my campaigns, and as of fourth level, I've used every feat on enhancing and expanding my skill selection, and my utility power is Astral Voice – improving my *Diplomacy*, not my combat ability.
So, these characters DON'T have Profession skills. And I can't give them Craft skills - and I know that there are people for whom that's a severe loss. However, both do have mechanical abilities that reflect their diverse backgrounds, and they're just two examples of what you can do. I've seen a lot of posts saying that 4E characters are inherently cookie-cutter images of one another, that the game is simply a tactical wargame; my point is that it IS possible to develop characters whose game abilities reflect their past and play a role in their present.
But again, that's just me rambling. ;-)