But let's see... more modular design.
That 'sameness' between classes makes designing them a lot easier and allows for more variance within the class. This is -good- design, as it makes it a lot easier to fit the pieces together, for the players and people running the game.
Compare, for example, a fighter and a wizard. In old editions, you would say the difference between them is that Fighters use the combat system, and wizards use the spell system. But that doesn't tell you -what they do- or -what their point is.- It doesn't point to a direction for the class, but rather a lack of direction.
On top of that, you have to make sure that entire systems are balanced against each other. As it turns out, the spell system was -heavily- imbalanced in comparison to the combat system, so you even had to have separate systems to accomodate character advancement.
And yet, none of this answers the question of -what they are supposed to do.- As a result, the lack of direction in the spell system meant that it can (and was) used to do everything any other system could accomodate, it's unique trait was that it trumped other systems by replacing them entirely with a simple 'I do this, it is done.'
Contrast this with modular design (which is 4e is going more towards) where the sameness of the base system allows for the differences between what the class -does- to shine. Fighter locks people down around them, and has a lot of positioning abilities, combined with large weapon-based damage. Wizard has a considerable amount of AoE fight, with inevitable damage abilities and debuffs that punish an enemy for opposing you.
The differences are thusly highlighted, allowing the classes to show their differences by what they accomplish rather than the neato mechanics used to support them.
Look again at second edition psionics. Most people balked at them because the system that supported them was terrible. So much so, they put out a -second- system that was less terrible (tho still terrible.) The system tainted people's view of psionics so much that when completely different and less broken mechanics get introduced, that taint of terrible -still- makes people go 'eh, never liked psionics.'
So in the future, integrating more modularity where possible is a good thing.
I do agree, however, that more attention to miscellaneous cool 'Quality of Life' items is a key of importance. I rather like handing out Bags of Holding and stuff that doesn't make fights swing more, but rather just improves how a character can deal with non-combat, or just generally be cool.
As well, a system for non-combat resolution that dovetails with combat even nicer than the current system would be nice. I wouldn't want it de-granularized down much further than it is... but perhaps a system of two classes, one being your battle class (Fighter, Rogue) and another representing your skill-set (Acrobat, Diplomat, Trapmaster) with its own subset of utility powers would be an interesting direction to go.