Let me preface this by saying that I'm 28. I've had access to the internet since I was in 7th grade in the early 1990's. While I do remember the time before the internet, I have been using it for more than half my life.
I hate PDFs.Rather, I hate e-books. I don't like trying to read a book on my computer screen. I like to hold the book in my hands. I like to buy books off bookshelves. I like to lug around bags that are heavy with books. I like worn covers. I like manual adjustments to gaming charts done in pencil.I like physical shelves with physical books on them.
While I'm sure you're rolling your eyes at my sentimental attitude right now, I do have issues with PDFs from a practical perspective. I don't own a laptop. I'm not sure anyone in my group owns a laptop, except for Kurt, and he plays remotely from Kentucky, so his laptop would be of no use in this instance. Without a laptop, there is no easy, quick way for me to reference a book on PDF. When my campaign had moved to the alternate world of Tarraxian, I used materials from Mutant Future, but I found that not being able to have a physical book on the table was a huge hassle. Ditto that with OSRIC, which I often ran to when the AD&D DMG wasn't yielding a quick or well-organized answer to a question that came up during play. I need my material at the table, within arm's reach. I'm not willing to drop $250+ on a widget that allows me to do so. (Think of how many books I could buy with that!)
I cannot easily loan an e-book or PDF to a friend.
I don't want all my eggs in one basket, a la Kindle. (Actually, they aren't really in your basket, they are on Amazon's farm, and you can put the eggs in your basket when you want to- oh, you get the point... let's not continue this tortured metaphor.)
I did once enjoy a PDF so much that I printed the book, bound it with a clip, and had it on my shelf. This is not a solution I was pleased with and would not do this again, though I might be willing to print off a particular page that contained a character class, map, etc. Still, this is, in my opinion, a jury-rig style solution at best.
I don't like the idea that publishers are moving away from traditional printing. I don't like the notion that we are moving toward e-readers. I hope I never see the day when books are antiques and you go to the public library or the e-book store and download something onto a widget, which is where you keep all your other books.
Call it fuddy-duddyism, or eccentricity, or simply an unwillingness to embrace change... I'll own up to it.
I know that paper books aren't going to vanish overnight, and perhaps they won't vanish entirely... but even POD won't be the same for me; POD means less bookstores.
I don't think my opinions are unreasonable, and I do see the merits of PDFs... I just don't see them as a replacement for books, and I certainly find them less attractive for gaming (or general reading) purposes than the "old school" dead tree counterpart.