However, if you compare the Computer with the TV, wouldn't you think the computer can/is a lot more intellectually stimulatin'? Also, some games do require a certain level of thought, which IMO is an intellectual stimulant (eg:Myst for a lack of a better idea). As to books, well I only seem them really, like you mentioned, improvin' your linguistic/writing skills and as a form of cheap fun.
I guess it depends a lot on POVs, but I do think that serious Sci-fi/RP'ers are of above average intelligence (and by serious I mean those who don't play RPG games or read fantasy books simply for the mindless hack 'n slash). Just for reference, fantasy books I enjoyed readin' the most were R.A.Salvatore's Drizzt novels and Margaret Weis/Tracy Hickman's Dragonlance stories..