I think you missed the point.
I was specifically asking those who felt the imbalance between spellcasters and non-casters only appeared with 3e, whether they thought breaking the mold (i.e. a radical departure from the way these classes worked in all the previous editions, not just 3e) was necessary.
I was referring to 4e's power system, not the customization or lack thereof.
Needless to say, the following is only my opinion.
AS someone who believes 3e broke spellcasting, I think 4e's system makes more sense for what modern gamers want.
Two of the restrictions on spellcasting was simply that a) wizards didn't get to choose their spells and b) magic items were not something that a player could easily control.
The DMG in previous editions hammered the point that magic items AND (something many people forget) spells were supposed to be carefully controlled by the DM.
Players nowadays expect control not just over their items but their spells. IT's the latter I think which is the biggest problem in rebalancing 3rd. A spell like KNOCK is balanced in 1e/2e due to rarity but not so much in 3e with it not only being common but also easily slottable via wands/scrolls.
re: 3e muliticlassing
Can't see how 3e multiclassing is considered an essential part of D&D. It basically turned D&D into a point buy system basically (every level purchase this amount of abilities)