That's a very binary choice that need not be so extreme. You can have wizards in the game without at-will magic, and keep the high-magic fans happy through all sorts of methods (themes, warlocks, etc.).
The problem here is that you aren't making either the high magic or the
low magic fans happy. I'm suggesting switches and options that allow you to pick the height of magic in your game. You can have wizards in the game without at will abilities - which means that the high magic fans won't be happy. And you have wizards with a pile of effective and choosable magic with very little cost or drawback. Which means low magic fans won't be happy.
As compromises go, it might have the benefit of appealing to no one. Except that it's not appealing to no one, it's appealing to the Traditionalists. This isn't a compromise.
A compromise would at the very least be to allow wizards to trade out their at will spells for an extra couple of low level spells. And then giving the DM control of that switch.
The choice doesn't need to between "allow at-will magic" and "BAN ALL SPELLCASTERS."
I wasn't saying ban all spellcasters. I explicitely mentioned leaving the bard as a caster. What I said was ban all primary casters if you want to make a low magic game.
Some folks want to keep magic as something the PC's can access without being something that any PC who accesses automatically treats as disposable. Those folks can easily be accommodated without inconveniencing anyone else, so they probably should be.
There are times in 3.X where magic is quite literally "Use it or lose it" thanks to the magical recharge systems. That's an even cheaper cost than free.
I don't see why there is resistance to the idea that the one point of contention can just be turned off by those who don't want it. From what's been said, the wizard WAS that way, and Mearls STILL wants it to be an option at some point, and it should really not be hard to stick the at-will magic somewhere other than automatically in the Wizard class.
The wizard is not, has never been, and will never be a genuine low magic class. Now you can allow the Vancian wizard without at wills on the grounds of
Tradition. But for low magic, magic needs to have a genuine cost or to be genuinely rare. Not something that a class gets a dump truck full of every day with only a token cost and that are their primary rather than their reserve means of problem solving.
Wizard classes in low magic games look more like WFRP (2e or 3e) or DCC classes - magic being unpredictable and having blowback. Or ritual casters. Or even 3.X bards where even the casters will use their non-magical skills before breaking out the magic - because in many cases the magic is best used to supplement rather than replace the mundane, and the effects aren't objectively that powerful. Or 4.X ritualists where you pay time and money rather than simply six seconds at the point of need to cast just about any spell.
It's easy, it's fair, and it sounds like it would be widely accepted if that were the case.
It fails to make the wizard a high magic class and fails to make it a low magic one. The only people this would keep happy are those looking for Traditional D&D Magic. It's easy, it's not fair, and it would be unlikely to be accepted IMO