I had over 25,000 and I deleted enough to get in and then checked my purchases and added what I wanted.
Lets be real, when we have libraries this big most of us don't listen on a REGULAR basis to all the songs in the library.
You might want access to those songs but why not pick the songs out of albums you like the most and delete a lot of the stuff you know you'll never listen to and enjoy this service.
Create a library of stuff that you KNOW you'll listen to and add maybe stuff in until you reach the max.
The majority of people that own libraries larger than 25,000 songs haven't listen to all the songs in their libraries, much less more than a couple of times.
We just want access to them.