There are a lot of useful ideas already forming in this thread. I especially like the breaking down of the 4E roles in to component parts, and the references to different infantry types.
The thing 4E did was put the design elements of the game where everyone can see them. Whether or not this is a turnoff doesn't lessen their value for discussing design.
4E got the roles wrong, though not entirely. The fighter isn't a defender, despite the historical term of
meat shield. He is the armored knight. The slow, but nearly invulnerable killing machine. The reason he soaks so much damage is because the enemy cannot afford to ignore him and he can't just move away. Nobody should be taking or causing more overall damage than the fighter. He should also excel at combat maneuvers. The area around him is incredibly dangerous.
The rogue as striker works well enough. He is light infantry. His job is to be where he is needed, so mobility is key. He has sneak attack because he's not supposed to stick around. He has to do his damage quickly and move on. In many ways, he's the one that should be defending the wizard, by showing up any time the wizard finds himself in trouble. The rogue's abilities should focus on mobility. Give him the ability to sprint someplace, dodge attacks, and still perform a solid strike when he arrives.
The wizard isn't really a controller, though he can be. Most wizards focus at least somewhat on big area of effect damage spells. That's heavy artillery. They also have summoning (reinforcements), divination (overwatch), and many other fancy tools. Their role is to be a powerful, multi-purpose resource that needs to be protected.
The cleric is a little bit of all three, plus a healer. It's a support role. The cleric can fill a gap in a pinch, and can make the other classes stronger and the enemies weaker. Some people don't like playing a support role, but for those who do, the Cleric always has something he can be doing.
But there are other, very useful roles that can be filled. An archer can put damage anywhere on the battlefield while staying in a protected position. It's a form of suppression, but doesn't function as well as it could. Imagine if a bow was incredibly powerful, but cover was much more effective, and shooting into melee was always dangerous.
A paladin can be cavalry, combining the power of the fighter with the mobility of a rogue and some of the support capacity of the cleric. The druid can beast shape to fulfill multiple roles.
And many classes, such as the barbarian and monk sit somewhere between the fighter and the rogue, and could be considered medium infantry.
So the roles, really should be:
- Heavy
- Mobile
- Support
- Suppression
- Special
And special is really just a catch-all. Most classes would likely have an element of it. The wizard is just the master of it.