These threads pop up all the time and it's always someone talking out of their ass. Here's the deal:
-The congregation library is supposed to have as complete a library (wrt to WT publications) as possible. They are not taking books out of the library and destroying them.
-If the literature counter has damaged items, they are to be destroyed. If the lit counter has an excess of old literature, they're supposed to try and use it in the ministry. That typically doesn't happen so it gets destroyed since that's really the only option left. Books from the 90's such as what the OP mentions are probably going to be old looking and yellow so those aren't really useful for anything.
and the person above mentioned donating books to the library: They were probably not needed in the library so what else were they supposed to do with them?
There's no conspiracy to get rid of old publications and hide stuff (that's what reprints and the WOL is for :) ). If you want to read the weird shit in Russel's stuff or Franz's wacky number stuff go right ahead. Those books are still in the library.