I'll engage with the struggle session: I think these distinctions are good actually, as they clarify the gradients between a bicycle and a moped. The 20mph speed limit in particular I think is a pretty important safety feature to have, and a reasonable speed limit on bike paths. The difference between 20mph and 28mph is not trivial, you're doubling your kinetic energy.
I do agree that Class 3 without a throttle is silly, I think that's a state-specific rule.