I vehemently disagree. Multiple classes should be good in combat.
Right... I'll agree that combat is a large part of D&D. There are going to be many classes good at it, but when you distill them down, they're almost always "fighter with a different flavor/approach/other non-combat stuff."
Fighters should also be good outside of combat.
Meh? I think I disagree. It's right there in the name:
Fighter. If you want to be good at other stuff, too, don't play a fighter. Or multiclass. Or some other option. But the default stance of the fighter should be all about fighting.
I honestly think that the decision to be "good" in combat should be available to all classes, because not all campaigns will evenly balance the three prime elements.
You're right, they won't. But that doesn't mean that everyone should be able to be good at everything.
You are not your class. If they have any kind of functional multiclassing, this should be an obvious statement. Fighters should be, to use your metrics, 100/0/0 (or close to it). If you want more variety, invoke multiclassing. In this manner, if you want a mage who has some combat skill, take a level of fighter... likewise, if you want a fighter good at social stuff, take a level in a class that is good at that. Treat the classes more as parts of a buffet that each level grants you things that say "I am good at X," rather than considering them as strait-jackets.
I don't want to see people start going "well if you play a combat heavy game you have to be a fighter, if you play an exploration heavy game you have to be a rogue." That's an even worse use of roles than 4e, in fact it's even worse than most MMOs.
You don't "play a fighter." You play a character with fighter levels. An important distinction. This (hopefully) isn't going to be 4e with its weird roles and heavy-handed restrictions and take on multiclassing. Character design via classes will hopefully be a lot more fluid, similar to 3.5, without the higher-level fail that that method entailed.
There's been a lot of discussion about "what is an assassin", and some of the premises people have presented don't even involve damage. Some are the "silent killer" guy who studies his enemy for weeks and then makes a single SoD attack in the dark of the night. Some are more of a "damage dealing" guy.
I'm not really sure what I think an assassin should be, but it would be a useful dumping ground for the rogue's combat ability. *shrug*
See, I on't want to see clone-variant classes get their own class. I'm a big favor of having a few "base" classes and each one having archetypes or builds or just bits and pieces that people can use to construct what they think the class should be.
In which case you would probably be of the opinion that the few base classes should cover as different ground as possible to ensure maximum coverage of the in-between areas.
It doesn't make sense, in that vision, that both fighters and rogues should have combat ability, even if it's different. Rogues should be more exploration-focused, and fighters combat-focused. If you want to mix and match, then mix and match classes.