Hell yes. I can't count how many users I know (or know of) who treat their own data with much less regard than for instance MS via Skydrive (Onedrive).
Play 'devils advocate' all you want.........one day soon it'll be yet another kona-contradiction eh? hehe
true. particularly on the Wincustomize forums you have many "i would never use cloud storage! my privacy!"-folks. and then you see the very same people posting very intimate details about their income, family, health, etc. on a public forum where every bot/crawler can read them. those are the same folks that think they're smart because they don't use social networks as they care about their privacy. 
besides that Yandex (i use Yandex.Disk) servers are likely more safe from hardware failure than my own computer.
(of course one still should think twice about what kind of data one uploads to somebody elses server)
