We know why some people uses modified clients:
  • higher polycount avatars (is not more reason now)
Now i see lately more use for:
  • steal avatars (very bad!)
  • immunity to blocks and kicks (VERY bad!)
  • change other avatars on purpose (VERY VERY bad) so they will stuck or breaking TOS on stream.
  • overload / crash clients
  • kick others login
  • steal worlds
  • entering locked worlds?
  • flying around without limits through worlds?
etc....
Because it happens more often lately in public rooms, i hope VRChat should make clients less moddable and more protected internally against modifications. WHY should you use modified clients? It will only damage VRChat community. You don't need it, it is used mainly for bad and wrong purposes!
Do you want VRChat add anti-cheat tools? Not all people likes it, but we might have no other choices.