Killers with useless or unnecessary mechanics

1. Billy heat dissipation and related addons - Yea these addons don’t really matter nor does heat dissipation in general usually. You can just quickly tap the chainsaw if needed to prevent heat from dissipating. These addons should be changed to something else.
2. Bubba tantrum meter - I don't think this is really an issue, while it's not that impactful against camping, it is pretty much the only thing it matters for at all. If you accidentally fill up the tantrum meter while in chase then you are probably not using his chainsaw correctly. I think tantrums in general should be a little bit shorter though (or at least when hitting a wall).
3. Wesker infection hindered effect - If you removed the hindered from infection then I feel like it'd be too easy for injured survivors to just ignore it since they don't care about the one-shot if they're already injured. While the infection will still reduce Wesker's power recharge time a little, it's not really much of a hindrance to that survivor specifically. I'd rather directly do something about its effectiveness for tunneling instead such as not allowing it to progress after getting unhooked until taking a conspicuous action.
4. Skull Merchant drones being immediately recallable after a hack - I would say that at the moment drone hacking isn't rewarding enough for survivors and doesn't have enough drawbacks for the Skull Merchant. Ultimately though, my opinion is that this is just one component of how poorly designed Skull Merchant is in general. She needs a LOT of changes.

"Even Nemesis's disease is stronger than wesker's not taking hindered into account." In what way? Nemesis's infection does absolutely nothing except allow for the tentacle to damage survivors. I wish being infected hindered the survivors in some way. LIke, for example, zombies move 50% faster when chasing infected survivors

Zombies move at, like, 2.0 m/s by default. If they're moving 50% faster than they usually do with this suggestion, that's 3.0 m/s. Strong, but not worth losing it over. His zombie movement speed addons would probably need an adjustment but you're grossly exaggerating.

Zombies actually move at 1 meter per second, or 25% of survivor running speed

Wait, really? There's no way they're that slow. I could have sworn you could get them to move at almost 4.0 with shattered badge and ink ribbon.

1. These are placeholder add-ons at best. I hope to see them reworked.
2. It's an anti facecamp measure, similar to Billy's old Overheat but actually punishes you for revving the chainsaw in front of a hooked survivor rather than punishing you for using the chainsaw to begin with. I think it's a good mechanic.
3. It's what mainly encourages survivors to use a spray rather than staying injured and fully infected at once. I do believe there should be something to discourage Wesker from tunneling, like pausing the Uroboros meter when a survivor is downed or hooked with a 15 second linger after the unhook or being picked up, or making his power recharge a bit faster per fully infected survivor instead of Hindered.
4. 100% agree on this, hacking drones should be more rewarding.

I reckon that the tantrum meter on Bubba is responsible for him going randomly into tantrum and then losing the ability to use his power for the rest of the game, so that definitely isn't useless. It's just not a good thing. I also reckon they introduced it so that, like Billy, he couldn't face camp hooks with a 99ed chainsaw. Only that issue has been solved anyway and now it makes no difference anymore.

With everything else on your list, I agree. I'd also add a part of SIngularity's anti camping mechanic. When you are still next to a hook, you can't use your power to quickly slipstream and teleport away, which is the exact opposite of camping. They could just make it so that only biopods in a certain range around the hook are affected.

Its true, I had a Nemi match where I was just on my a game, 3-gen chase. Somehow didn't see any zombies for the first 2 gens, the 3rd one popped and I got pincer attacked by both zombies + Nemi and essentially insta -downed after the zombies appeared out of thin air. Funniest thing I've seen in a long time, I screamed so loud I'm surprised my neighbors didn't call the cops out of concern. That Nemi needed to give those zombies a raise.