Do pros really want to store their photos "in the cloud"? I'm just an amateur and have ~500GB of photos. Uploading that much is almost impossible over a normal asymmetric home internet connection, and I imagine professional photographers must have multi-terabytes of data easily.
Having the security and knowledge that 500GB of your precious photos are stored off-site multi-redundancy, blah blah, vs your own hard drives definitely seems worth it to me.
I mean, one flood and kiss 500GB of photos gone. That would be a very sad thing indeed.