My main argument in favor of e-readers is the same as that for the iPod: you can cram a lot of reading material into a very small space. Anybody who has ever had to tote crate after crate of LPs to college can fully appreciate the technological marvel that is the MP3 player; ditto on the e-reader for anyone who has saved money on moving by renting a U-Haul for their book collection instead of having the movers take them. (
Also, you can easily change the font size on an e-reader, which gets to be a bigger issue as you get older.
My main objection to the e-reader setup is that you can't easily loan, trade, or sell back e-books. I'm pickier about what I buy because I know I can't sell it to McKay's later on.