The Bottlenecks Are Dying
There are a number of reasons why online backups and online storage failed during the original dot-com boom. Some of these are management-related; some were around the fact that few users had any use for 10MB of space that they could get to only via dialup connections. The biggest bottlenecks were storage costs at the hosts (hence, 10MB of space instead of 10GB), cost of bandwidth at the host, overall broadband availability, and awareness of the need to back up data at home or in a small business.
Everyone knows how much storage costs have dropped. Not only have they dropped, but new technology means that extra capacity on individual servers can be clustered together, as opposed to needing to buy massive dedicated storage units. This situation has allowed newer startups, as well as established infrastructure players, to deliver solutions of 20GB–100GB for the same cost to their business as 20MB–50MB would have cost them just 6 or 7 years ago.
In addition, the plummeting costs of enterprise bandwidth (from $5000/Mbps to less than $500/Mbps) meant that extra storage is suddenly much more available. In fact, it really means that the cost of managing an online GB of storage is nearly $0. If you thought 2GB of Gmail space was a lot, how about when it hits 1TB in 5 years? Soon and very soon, the cost of storage will be so low that it might as well be free.
The final piece of the puzzle, then, has been an increased awareness by users of how critically important backups are. Part of this is surely due to how much more data a typical user keeps (photos, emails, jokes, home videos), and part is almost certainly due to the rise of the home worker and telecommuter. The more data we have and the more mobile we are, the more critical solid backups become.