(raises hand) I chose wizard over warlock. I wanted to be able to cast more than 2 spells per encounter, and I wanted a larger variety of spells at my fingertips. I don't feel like I was being 'punished' for that choice at all.The problem I can see is that you will get what you reward. No player is going to take a long rest PC over a short rest PC. Why would I take a wizard over a warlock? If I'm being punished by making a choice at your table, then I would not take it.
So your saying, 2 long rests per level OR whenever players go into downtime?By definition, "Downtime" means there is no adventure. Not a combat one anyway. So when the players do start a new combat adventure, they start fresh - as is already normal now.
If players end an adventure to go into Downtime, it means the players chose to abandon the adventure.
You might feel punished if you can only regain your spells twice per level like what was proposed. I myself like wizard over warlock for what you are saying, but taking the ability to get spells back as often as before will make me not take it.(raises hand) I chose wizard over warlock. I wanted to be able to cast more than 2 spells per encounter, and I wanted a larger variety of spells at my fingertips. I don't feel like I was being 'punished' for that choice at all.
I've played a warlock before, though. It was a lot of fun, but it got really monotonous: cast my spell in round 1, cast my other spell in round 2, then spam Eldritch Blast for the rest of the battle. Take a short rest, repeat.