Some of the ones I kept I've read already, some I don't know if I ever will, but I held on to them because they were gifts or signed or both.
If they'd all been ebooks (there's nothing wrong with electronic signatures and dedications), it would have been much easier to keep them all. Just disconnect my ereader, move some files to the cloud if I'm running out of storage, and never delete anything I like ever again.
My mom has a rather impressive and oppressive collection of cookbooks, too. She's been slowly going through them and whittling them away, but likes to have them around for reference. Ebooks would be perfect: available to leaf through when uninspired and searchable when locating that half-remembered recipe. And then they wouldn't be littering every flat surface when I come over for dinner!
There's nothing quite as nice as delicately poring over a hardcover with color inserts from the 1930s, but for condo living or frequent moving, ebooks are the only practical way to go.
An additional note: next week, I'll be vacationing in Florida, so my friend Patrick Thunstrom has agreed to provide a guest post.