I'm going to assume you never read electronic books or use electronic videogame guides if you have to ask that. Reading books on a desktop computer screen gets old fast. There's also the possibility you carry a Win/Mac computer around everywhere you go, but I seriously doubt that.
(I carry a thumbdrive around with 17 Operating Systems +sorted tools (SARDU), but carrying around a whole laptop computer along with my PSP(cracked for reading, videos, everything), 3DS(playing OoT and Icarus currently) and a dumbphone for emergencies would be a little too much. I'd rather only carry only one, 3DS or PSP at a time, but the PSP can view the text guides and e-books I want to read, and I want to play the 3DS)
I can't even really imagine using a laptop comfortably on a bus, bench, or sitting on the ground o.0