you only think the name doesn't make sense because you're not old enough to remember what came before. in the olden days, serious foot retention was done with a combination of slotted cleats, toe clips and straps. when look came out with their first retention system, the really noticable thing about it was that there were no toe clips. hence the name clipless.

really, my theory is that in cycling if the name implies it exists, it doesn't and vice versa. ie clipless actually clip and tubulars actually have no tubes.