It is probably a combination of hitting a (low) cost and mimo; cisco makes pretty reasonable looking APs with lots of radios and decent coverage and they look like UFOs not alien spiders.
But it's probably easier / cheaper to get maximum coverage at larger distances from a single AP using a big array of sticking out antennae, and that's what a normal home user is going to want.
I feel like there's an untapped market here. I want them to go with the alien spaceship concept all the way thru; I wanna see mini Death Star mesh nodes, X Wing routers and Millennium Falcon access points, dammit. Or hell, cross the multiverse and give me Borg Cube mesh nodes, complete with green shiny LEDs that actually indiacte network/hardware status.
But it's probably easier / cheaper to get maximum coverage at larger distances from a single AP using a big array of sticking out antennae, and that's what a normal home user is going to want.