I am against mods that impact the performance of the servers, but there are some custom mods that should definitely be implemented that, conceptually, don't impact server/client performance:
  • Support for more than 6 point tracking (enabling elbow and knee tracking);
  • Fullbody calibration saving (saves calibration between avatars so it doesn't need to be done everytime avatars are changed);
  • Change VR Menu based on head position (If someone is laying down the menu appears on top instead of inside the chest);
  • Showing pictures during the loading screens;
  • Changing the resolution of pictures taken;
  • Toggling walking/running animations on the fly, intead of leaving that decision to the avatar creator;
There are also some mods that affect some client performance, but are worth it in my opinion:
  • Portable mirror (being only shown locally, and being a toggle);
  • Global dynamic bones (affect the performance of the person that activates it, but being a toggle, the user itself has the choice).
Of course there are, imo, "malevolent" mods that are immoral and shouldn't be implemented, but just because those exist, doesn't mean the reputation of all of the above should diminish.
I think the best course of action would be, at least, for there to exist some sort of communication between the people that made these mods and the vrchat devs. It wouldn't be surprising to me if they chose to help the devs implement them in the best way possible.