I've been with Digital Ocean for over a year, and I'm fairly certain that I haven't had any downtime at all. The site is used by thousands of users a day, and I've never had any complaints. Pingdom is set to a resolution of 1 minute, and hasn't reported any outages either (that weren't caused by me).
DO droplets do have more disk space for your dollar, but AWS's answer to bulk data storage is S3, which is very cheap itself.
The main point is that S3 egress costs are substantial for bandwidth-intensive applications.
I take your point, though this being said, it again comes down to use case. A couple of hundred dollars a month for bandwidth is nothing for a business above a certain size, but it's tons for personal use. Depending on your use case, it may be also far more effective to use S3 and simply pay the data bill, rather than architect a system distributed across a ton of droplets.