Their "mistake" was to separate damage from every role and make it seem like that was the "strikers" only province.
In a redesigned game I'd like to see the 4 roles still be as they are today, but the defender should be the heavy armor/high defense striker, and the striker should be the light armor/high defense striker. The leader should be the "inspiring" striker, and the controller should be the "controlling" striker.
Multi-ability dependent classes should be taken to the shed and.... Remove the dependency on multiple abilities from classes. Each class can have one or two abilities that are primary for it. Pick one and that is your primary ability. No muss, no fuss.
The heavy armor and light armor paths should be "features" of the martial classes. So you could select either, and still be well protected because of your choice. If there is a shield for the heavy armor defender then there should be a parrying blade for the light armor defender. Both grant a "shield" bonus that is non-stacking. Or you could make a "shielding/defending" style that covers both and you don't depend on equipment at all. If you pick up a shield you're protected, if you pickup a parrying blade, the same.
All classes should have some viable melee and long range combinations(builds), with specialist builds that are slightly better in either role (sniper, duelists, etc.)
Doing damage is what ALL classes should be able to do. This would start taking care or the perceived grind. If a wizard uses an area spell they should do average damage to multiple creatures, but if he uses a single creature spell is should do STRIKER damage to that creature. Both options should be viable. Some of the long range attacks from other classes should work like area attacks, doing average damage to multiple creatures.
There should be no class skills in the "restricted" sense. Every skill is available to every class, there are some classes that are simply better at certain skills. So a fighter that wants to spend some time studying arcana is fine. He's already limited in his skill points so if he wants to spend them in that fashion that is the player's prerogative. The wizard would still be better with inherent "class features" for Arcana.