They're useful in slowing down players approaching your high ground if they're following you up your ramps (they have to build around it or shoot it out).

You can slow players down early game by placing traps in rooms etc forcing them to shoot it out (and give away their location) or find another path. Especially useful if you're being chased upon landing.

Can fortify your base if someone tries to launchpad, impulse, or build into it (although only used to catch people off guard, works sometimes).

Used to kill/damage people hiding behind doors or other objects in a room (doesn't apply to only potatoes).

Traps actually feel the least useful at the end of the game when there are only 3-5 players left. Pros like yourself just never need to/remember to use them during the mid game since they're kind of cheesy/excessive and also provide less actual action for your stream.