Because hardware is hard. There's a learning curve that requires a time investment before you can do anything cool. Anything that starts to tear down that learning curve is a step in the right direction.

Do you honestly think that there is anyone out there who bought a Tessel instead of an Arduino/Raspberry/etc.? Every single person I know who ordered a Tessel is someone who wasn't interested in hardware originally AT ALL. The premise of the Tessel got them interested in playing around with hardware.

Edit: I answered this seriously because I assumed OP was a serious comment. After re-reading, I'm not certain, so I apologize if it wasn't.