I found a two year old post saying that the only way to do that was to contact support and request it.. I hope that's been fixed since then, but I can't see anything saying so.
Anyway, my reason is simple: I bought the current Queer Bundle, but there are a number of games in it that I have no interest in at all
I liked that for the BLM bundle I could add the items i wanted to the library by just browsing for them in the bundle list, skipping titles I didn't want. This time they were all added directly with no intermediary.
There are several games I *do* want, but more than enough that I don't want and would never play that are just cluttering my library for no good reason.