"Currently thinking about ways to totally redo skill training, removing the randomness and annoyance. Anyone have a contribution? " - Aristox
Botting is a huge problem, especially when it comes to skills. Can you blame them? No, because it's bapting awful. Let's be completely honest - no one uses half their skills before working on them for legendary because they're useless.
Remove skill training entirely(minus weapons - these are fine).
Allow classes to learn generic skills while leveling and have to quest to learn others (in a Paladin's case, maybe rally, guard, righteous will(already quest), beseech are quested).