[throwaway219450]

Being circular allows for zero clearance turns.

If you imagine a square robot traversing a wall and approaching a 90 degree inside corner, it can’t make the turn and would also be unable to make a perpendicular move to get more space.

That said Eufy, Makita and others make square-ish robots.

[mohamedkoubaa]

It can easily make the turn if only one quadrant was square and it didn't approach the wall with that quadrant pointing forward