I work at 18F and can assure you that if data.gov was brought down, there is a good reason. I don't know the specifics for their team, but there are many factors that would warrant bringing down a site. For example: monthly billing, contract renewals, legal, security and compliance requirements, etc. This is not a side project that you can step away from and assume everything is okay because it's "on the cloud." It doesn't take much imagination to think of why: Let's say the site gets hacked, who would restore it? Would it remain hacked for weeks? months? How about contracts? Do we expect legal dept to just ignore expired contracts?
It doesn't work that way.
The thing about government is that there isn't much wiggle room to improvise on those kinds of issues. You are either following the law or you are not.
Fortunately, the product I lead has not yet been affected, but the possibility of having to bring down sites looms.