I think that you get to the issue here.Just make them different classes and lock in the mechanics, for crying out loud. For arcane: Vancian = Wizard. Non-Vancian = Sorcerer. For divine: Vancian = Cleric. Non-Vancian = Shaman.
Which seems simple enough, until someone tries to take the Vancian classes (which have a built-in disadvantage just by being Vancian) and make them non-Vancian, thereby getting the best of both without the drawbacks. Sorry, folks, if it's balance you want then every class has to have its advantages and drawbacks.
4e adopts the approach that you describe: wizards (who are quasi-Vancian) have their distinct backstory (spellbook using scholars), and their distinct role in the game (controllers and ritual casters); warlocks likewise (pact-forging strikers); and sorcerers (power-infused strikers).
But one aim of D&Dnext, as I understand it, is to divorce role from class, so that a wizard could be a striker, a controller, a leader, etc, depending on spell selection and player choices in the course of play. That is, story archetype and mechanical effect on play are being separated from one another. At that point, what is the rationale for keeping story archeype connected to spell-use mechanics?
If the answer is "balance", fair enough, but Mearls at present seems to be promising that a Vancian wizard can be balanced with a spell point wizard. Assuming that that design goal can be achieved, why is a default mechanic required?
This is a fair question. I think [MENTION=54877]Crazy Jerome[/MENTION] is right that, with good rulebook writing, the link between class and casting options need not be a wall of complexity. But even if that's so, you may be right that it's of the essence of warlocks and sorcerers that they play more simply than wizards. Even then, though, there might be some who prefer slot sorcerers or points sorcerers - in which case the same argument can be put that there is no special need for the game to establish a default (but of course it could say: if you want a simple sorcerer, go to the points-casting option on pXXX of the Spell Users chapter).Ok, maybe it could work FOR WIZARDS, sorcerers and warlocks have traditionally been way simpler than wizards, if the majority of sorcerer and warlock players just want to have a simple default in order to focus on all of the important choices (pacts, bloodlines, whihc spells/incantations to learn) do we win anything by hiding the simple caster behind a wall of complexity in order to please wizard players?