Why wouldn’t they? They have in the past. I myself would have considered upgrading to a paid account if I’d needed more space then what I got from referrals. Now, I’ll stay away from them out of sheer spite for being treated in such a backhanded way.

Well IMO we should treat Dropbox's new policy as indicative. Apparently many people were happy with the free tier and made it work -- me included; I initially had a big installers folder which I then offloaded to an external HDD because I wouldn't be able to have my more important files synced.

So Dropbox figured out people would continue to freeload forever and devised a strategy to try and convert some. That's my theory.