For those saying they want them to change Spell Versatility for Bards, Sorcerers and Warlocks to work for level up rather than long rest...that’s exactly how it works now.
Those classes already can only have an extremely small number of spells. 2, at lvl 1, 15 at lvl 20. That’s not a lot. Wizards have up to 6 at lvl 1, and 25 at lvl 20, and every ritual in their book, as well. And that’s a whole lot more. And Wizards have a much, much larger spell list to choose from, and can eventually learn ALL of them.
Allowing a being infused with magic, or a person connected to a powerful being, to switch up a single spell every long rest won’t overshadow the Wizard, it just solves what is an arbitrary nerf to these classes. Their philosophy of “You get what you get and you don’t throw a fit” was the biggest thing I had a hard time with, even though they are some of my favorite classes.
As for them knowing their whole list, technically, it makes sense for Sorcerers and Warlocks. Sorcerers do things on instinct, not learning, and Warlocks have a patron that teaches them power, so both have a leg up on a Wizard, who gets more prepared spells per day and a larger list to pick from, but who is limited to the spells in their book. Bards are a little more of a stretch, unless you figure they’re another kind of Sorcerer.