There are around 6 issues with equipment that are each individually total deal-breakers. Randomness and intense setup logistics (more than custom specials) is only one of them.But Bowser with speed equipment is also more fun. If equipment was non-random and everyone had the same equips, would we also want equipment on?
It's reasonable to practice against every character, and it's reasonable to practice against every (viable) custom special. It's not remotely reasonable to practice against all configurations of equipment, which affects the entire moveset of every character. (Including binary things like SH AC windows--it's not simply a spectrum)