As a used books seller, I confess to disliking inscriptions. I've been chastised by family and friends for tipping in a card when giving the gift of a book. I can't anymore bring myself to actually write in a book.
There are inscriptions and then there are inscriptions, of course. "Love from Aunt Dot" in pencil and dated "1879" is actually rather sweet -- and erase-able. But there are those who feel that the blank endpapers of a hardcover are just too much like actual stationary to resist letter writing. Of these scribblers, I despair.
I've just come across a fascinating site, dedicated to collecting inscriptions from books. The Book Inscriptions Project woulds seem to me to be one of those undertakings for which the Internet seems to have uniquely purposed. Check it out, when you have the chance.