Silicon Valley startups might not think it's a big deal, but being able to run entirely on a private network (either "behind a firewall", or an entirely disconnected network) is pretty huge. Without AeroFS, your choices today kind of suck, especially for 10-500 person companies (or bigger companies where your corporate option sucks or isn't available). Dropbox doesn't work if you care about security. You're left with various forms of SMB crap, more backend-type things like iSCSI, or either blasts from the past (nfs, afs) or science projects (zfs).