The developers (everyone) in a two-person startup?
Sure.
In a mature business with 50 employees? In an organization of that size do you really want your development team driving IT decisions (and budget)?
Of course, if you find that hosting takes a large % of your costs, and if you are sure you can do it yourself with less costs , then it's time to have your own hardware.
Amazon provides power, servers, bandwidth and their network.
You still need administrators and ops people. If you colo, your data-center will provide power and bandwidth. You just need your cabinet network and the servers.
On top of that, Amazon costs more, and expose you to problems like the EBS outage that you simply don't have with colocation because you haven't gone and developed a (probably necessarily) complex provisioning system to manage it all.
The implication in your statements is clear that the act of purchasing, provisioning and maintaining hardware is a primary driver of your IT/Operations work-load, when in reality that's a minority concern at best for most. It borders on misinformation.
A simpler option is to rent dedicated servers in 2 different hosting companies, say softlayer (US) and OVH (France) and design fall-back mechanism. It will cost you less than amazon or owning your own hardware.