I agree with those points but there's another side to it, of course: The economy of scale of service providers allows reliability, in important ways, that most people can't match by self-hosting.
Absolutely. Things that are very data heavy or require extreme planning, for example.
I'll shell out cash for hosted databases... even though I'm fine with building everything else myself. Topology stuff alone usually makes this worth it.
Virtual machines and snapshots can take you a long way, though :)
