Why can't other services work like email and Matrix and have success? A lot of it just seems like success of marketing to me.
I think part of it is just the ease of setting up services. You can install new programs on your desktop win/macos and they'll update themselves and all that, but servers are not so easy. There are things that are coming out that make servers more pluggable/lego brick build-able like Sandstorm, and maybe one of those will really take off and make hosted apps something more individuals would be willing to pay for.
E-mail also has its huge share of problems. Setting up your own e-mail server is also super unreliable because of over-aggressive spam filters, as I wrote about here:
http://penguindreams.org/blog/how-google-and-microsoft-made-...
Open, federated systems are possibly, arguably, better, both in terms of ideology (or alternative, more specific terms like "privacy") and (maybe) technology. But, as you say, users don't care about open/closed, they don't care about ideology, they don't even care about technology. They care about ease of use and appearance.
Open, federated systems will never be as simple as proprietary systems. Further, they'll never attract the money necessary to get even as close as possible in terms of ease of use and appearance. Non-proprietary systems will usually lose out of the gate, not because they're dragging a 100lb anvil of ideology but because the alternatives have a magic tailwind of simpler requirements and more resources. (And that's as pragmatic as you can get, right?)
Note: I'm not a Stallman-wannabe, I'm not wagging fingers (at the moment, on this issue), and I use proprietary solutions all the time. But I also know what I'm trading off.