Considering the point of the Raspberry Pi foundation is to provide a readily available low cost general computing platform for learning and experimentation, it seems entirely appropriate that people would port stuff to it for the sake of porting stuff to it.
To add to that, http://www.techdigest.tv/2013/10/10_gadgets_that.html shows examples on a Nintendo DS, TI-Nspire (your link is for the older TI-83+), an old Minolta digital camera, iPod Classic, Zune, a Commodore Vic 20, and others.