> Less massive objects like asteroids can have weird shapes, like the asteroid Toutatis which has a sort of dumbbell / unshelled peanut shape. The hydrostatic equibrium requirement prevents such objects from being classified as planets, as well as small objects that just happen to be round for other reasons.

Okay, and how did you arrive at the hydrostatic equilibrium requirement? What law of nature told you that planets must be spheroidal?

You're only adding this requirement so the outcome fits your pre-existing desired results, since you're literally arguing for the requirement based on what objects it excludes. And what are the consequences of such arbitrary decisions, according to you? "You can't get away with that in, say, physics and still end up with useful theories[...]"

Do you get the issue with this line of critique? There is literally no useful definition of "planet" that is non-arbitrary.