- We already have the expertise to do so, so the cost to us is much smaller
- We can ensure a much higher level of service by making sure every component along the line is up to par (you'd cry if you heard what some colo providers do)
- We can fix problems in-line with our priorities, since we're the ones that fix them (like keeping published sites up, even if the editor is down, for example)
- We can set up and manage geographically redundant datacenters
- And finally, we're able to do so extremely cheaply
It's definitely something to consider when you reach a certain scale, and especially if you have the know-how to get it done. We've calculated that for every server we purchase, we'd pay that cost every 2-3 months on AWS, for perspective.
I'd love to hear more, if you're at liberty to share.
and, worst of all, you're at their whim -- if they decide, for whatever reason, to unplug you, that's it. we prefer to eliminate anyone who has the ability to take our service down :)
Believe it or not, we've had botnet attacks that took down $100k Cisco routers. Nasty :(