On one page at the beginning or end would be fine, or better yet, non-visible metadata/stenography, but stamping my name on every page is like putting the FBI warning on movies. The only people who see the FBI warning are the legitimate purchasers. Stripping my name off each page of the PDF is a trivial technical challenge, something a dozen lines of Python could probably fix, but it's highly annoying that it's even necessary if I legitimately bought it.

It's also about how you apply it. PragProg is pretty subtle, Packt Publishing is (or was, it's been a while) was in your face about it.

I've been on the fence about buying this book for the last hour, and this is a factor that has me leaning towards not purchasing (besides there being few unbiased comments on the contents).