There are really great cheap SOC's out there, in ARM land, to play with.
Just look at these guys: http://www.acmesystems.it/aria
Look, the rPi started off as a play-thing for kids, and there is now a valid rPi generation. It is expanding as a platform. But: in the industrial world, the rPi is a small fish. You can get an rPi precisely because some other industry has already driven the demand/price/costs down for it to be affordable/profitable to build a new brand around what is, a common industry practice/device mind-set.