It doesn't help that Sandstorm focuses on apps that are architected with a devops-heavy mindset. Many apps don't really need anything more complicated than PUT and DELETE (no POST special handling required), esp. since they're already doing so much on the client, anyway. This really calls for an auth-protected document store more than it does what Sandstorm tries to provide; the difficulties of "getting people a server" probably starts with assuming/insisting that that's what you need to do in the first place.
Those kinds of architectures are only necessary when you really do need some way to offload computation to a remote, high-availability machine, but things like online image and document editors aren't that. (Even then, what you really want for that is some sort of mobile code architecture that lets you squirt lightweight payloads at some sort of fleet of faceless workers, preferably in the same/similar form to the kind of code that you write for doing useful work on the client...)
A huge issue is that the gatekeepers of "open source" don't believe making it financially viable is something they need to address. So it's gonna end up being the best we can do in our spare time for the love of progress.
Unfortunately, the problem is companies powered by ad revenue have a lot more money to throw at usability than FOSS folks do.