It makes it easier for them.
what does? housing mail outside the US? outside of their partner companies or previously breached companies (in the case of google).
I mean, if you have a remote server- it's lawful for them to snoop (by their own law), but it certainly makes it harder, to gain access and maintain access- as these systems may be wildly different and hosts will be varying degrees of paranoid.
We can, and we definitely should.