I have an EN-counter argument.
The way in which the Wizard uses magic says a lot about the nature of magic in the game. It doesn't have to be the only kind of magic, but I think most people agree that the most powerful, the most game-changing and reality-warping spells end up in the hand of the mage. Preparing spells daily leads to a Wizard that justifies his intelligence score - he has to have a powerful mind to contain these spells, and it takes careful thought to prepare them.
I could envisage a class that doesn't have to do this to cast spells, let's say the Sorcerer. They are naturally infused with magical power - like monsters, they don't have to study every morning to be able to lightning bolt you later in the day. They may still be tired out by casting spells, but give them five minutes and they are ready to go again.
Of course there are at-will spells too to consider. Popular because they give the Wizard something else to do during the day. They are obviously so easy to master that lots of people can do them (indeed all High Elves and Magic Users that aren't otherwise spellcasters can do this). They are tricks, avoiding the usual exhaustion or mental exertion required of magic.
Now, I say if you give the Wizard his minor spells, his special daily spells *and* spells he can regain quickly then not only is that adjusting one's concept of how magic functions in the world (spells basically have recovery times, none of this mental preparation stuff), but it also cramps the design space for classes such as the Sorcerer or Warlock.
So please, leave the Wizard with his daily, prepared spells. Give this encounter stuff to other classes.