For the most part I agree -- one reason I'm reading and typing this on a Thinkpad.
But let's talk about read-only tasks.
First, a lot of those are now easier on a tablet than on a PC. Faster booting up, simpler interface. Touch what you want, it opens, you read/watch it. At the moment, anyway, tablets have better screen quality.
Second, ease of use and screen quality mean that activities are migrating from print and TV/DVD to tablets. I read a lot of pdfs as part of my work. Like you I watch zero TV, but I'll sometimes unwind with 10 minutes of Daily Show and I've started to watch an occasional episode of "The Thick of It" on Hulu, which is available nowhere else. My wife reads books and watches video on laptops or tablets routinely.
Maps, reading for work or pleasure, looking things up, video ... there's a lot of read-only in most of our lives. I haven't quite made the move, but I'm planning on buying the next version of a Nexus 10 that comes out. At work, I've seen a lot of colleagues who used to turn up at meetings with laptops bringing tablets.