Many people are calling this a bait and switch, and it's hard to disagree, even the paid plans have had their storage capacities slashed.
Why offer 15GB and camera roll extras and other things you could do to increase your limit if they can't cope? Why blame this on a few users who are using the "unlimited" space as they are perfectly entitled? Why not put a cap on the top end of 1TB or 5TB and leave everyone else alone? This all smells decidedly iffy.