Is Minecraft only for kids?

I don't think it's for kids, I just think it is played by kids.

Alot of adults use it and I've even heard a heap of architects use it to model buildings.

Take the modding community, and technical community as well breaking apart the game code to find the absolute best ways to do things.

I don't think minecraft would be what it is without the adults or older people player it, think about what attracts kids to minecraft, either their friends tell them about it or they see someone older playing it doing crazy stuff. Kids don't play minecraft because they watch kids play it.