What purpose should comeliness serve?
Why should someone assign attributes just to be handsome? This will only bring back very ugly fighters and mages.
Charisma now in 4e actually does enough to be considered when creating a character. Even in 3rd edition it was no stat to dump as a fighter:
want to be intimidating: be charismatic.
Don´t want to be being bullied around with "charm person", a level 1 spell: be charismatic!
I think you can do this, and frankly, don't need six scores -- three will do. But then, a lot of game systems already do this, and the six attributes are one of D&D's core identities.
I just don't think 3 or really even 6 can really sum up a person that well.
For instance, I have great reflexes but terrible manual dexterity. I have little stamina (and get sick easily) but am tough physically. I'm good at puzzling things out but have a terrible memory.
Comeliness is another great example - physical beauty compared to personality.
it may be better to make a passive and an active score:
attack: d20+modifier agains 10+modifier
and the modifier should not be +1/2 levels, but rather like the srength score in ADnD
Going up slightly in the normal human reachable range of 3-18. And then going up faster.
Or just make Giants really strong:
Str 24 would be quite lousy for a giant IMHO when humans can reach 18 easily.
It was ok in ADnD, because usually humans didn´t roll an 18, and when they did, they stil did not usually roll a really high number on the extraorsinary strength table. So while it was possible to have a human that was near giant strength, it was a 1 in 21600 chance to get 18/00, if you rolled 3d6 top to bottom.
If DnDn uses 3.5 style modfiers, i hope, that you don´t go over 18 and Giants have scores of 30+ at least. This way, you have a quite good relationship between stats and plausibility.