In every edition of D&D each class has its niche area that its best at. Rogues are best at being sneaking and getting in stealthy attacks or deceptive attacks, they open doors, disable traps, etc..etc... Fighters are big strong brutes that protect the other party members or smash enemies. Wizards are powerful but limited glass cannons. Clerics are warrior healers that are basically back up.

What if they made different roles for different classes though. So that you decide what you want your character to do first, then you decide how you want to do it when you pick a class.

I can see a Wizard tanking with a combination of well made spells like a spell that gives penalties to enemies if they don't attack the caster. Then spells like shield, mage armor, stone skin, mirror image, blur, blink, false life, etc..etc.. would allow the fragile Wizard to take hits and draw the attention of enemies.

A rogue could do something similar with taunts directed at enemies to draw their attention, then evasive maneuvers like full defense with reaction attacks like 4E's riposte power (it would have to be modified).

I could see a Fighter blaster/striker type being a ranged weapon specialist with certain feats that allow the throwing of one handed melee weapons and range enhancement features or feats or powers. So they would deal really nice damage by pulling out a great axe from their bag of holding and chucking it at the nearest enemy, possibly multiple times in a round.

An archer Ranger could be a controller by having certain powers or feats that allow rapidly shooting arrows over an area or pinning an enemy to the ground by shooting their foot or using specially made arrows to throw out a cloud of ash or pepper on impact to blind or irritate in an area.

What other kinds of role changes would you like to see or allow in your D&D games?

Just... no. Rogues are ineffectual idiots who are more likely to die than do their job, and their "job" is entirely superfluous, fighters are... just extra WBL and carrying capacity for the party, clerics are the best melee in the game, and wizards just win.
Play 3.5.
Sorcadin. You're welcome.
No, no it really couldn't.
Tome of Battle. Again, you're welcome.
That's a terrible idea. Rangers are actually usable as-is.
I don't need to. You see, and classes are what are known as "metamage constructs." They're meaningless in-game, because NPCs don't know their character sheet. Bob the tenth-level fighter doesn't introduce himself as "Bob the tenth-level fighter."

You don't need to change the classes to get what you want, you need to take the classes you want.

Less abrasively than CJ:

The roles don't matter much. I can make a "Warrior" who heals the party, along with some battlefield control. I can make a "Divine Caster" that can do ranged or frontline combat better than a fighter. And so on, and so on. What you want to do is not wholly dependent on your race/class choices; at least not in 3.5.