I always loved getting free writable floppies in the mail from them!
Their service was useless to me, but the floppies sure weren't.
Then they switched to CDs, which went directly from mailbox to trash,
and I was very sad.
Are you sure those CDs couldn't be re-used? I've got some promotional DVD that could still be re-used. It only had like 70MB written. You could just format it, and use the rest. I did that stuff multiple times. (But not all of them are recordable)
Once you get into serious quantity, getting a "plain" (Read-only) CD or DVD manufactured is much cheaper than rewritable. AOL was junkmail-bombing the entire country.
At the time, CD writers were not a common thing. Supposedly, CD-RW
that could be rewritten debuted in 1997. AOL wouldn't have been giving
those out. You paid a premium for them compared to the write-once CD-R,
which is what most people I knew who burned CDs at home were using.
AOL just sent mass-pressed CD-ROMs.
It would be interesting to know how much waste their CD mailing campaign produced.
I think it would be a nice gesture to recognize their accomplishment
with a monument: the Steve Case Memorial Landfill.