I have a drive that I may be away from (at least, my Macbook Air is) for weeks at a time, and I don't want to continually lose version history or have to reupload some of the larger files (home videos and my photos).
CrashPlan doesn't delete your backups after 30 days (they keep everything as long as you're subscribed), but the upload speed is so horrendously slow I couldn't upload the entire photo library plus videos (~300 GB or so) in the month I was subscribed. I'm on a gigabit network over Ethernet, so it's not my connection that's the issue (Backblaze, on the other hand, uploads this data very quickly).
I realize that they're trying to reduce costs by deleting data that doesn't seem to "be in use", but I'm sure a lot of people have "archival" data that they don't look at often, but really value.
Instead, I'm currently using Arq 4 (which is fantastic, by the way) with Amazon Glacier for the photos. It may cost something to retrieve them if my drive dies or is physically destroyed, but I'm not planning for that to happen. I have Arq set to use S3 for my other documents and such so I can restore versions whenever I need to, so it's really the best of both worlds.