Besides, Astoria will lead to a second-rate UX for Windows Phone (WP) as Android apps on WP are coded as per Android UX guidelines, not WP UX guidelines.
If Microsoft is building a framework, I'd expect it to provide a great UX for their users.
If a compatibility layer is required, it would be better for MS users to have it in the reverse direction, to let WP apps run on Android, and use that to try to convince devs to build WP apps.
In summary, it never made sense for MS to provide WP users (their own platform!) with a second-rate UX.
I don't think average user cares as much about uniform UX experience as they would from just being able to use the app. Example: Pokemon GO uses totally it's own UX on iOS and Android and that does not seem to harm it's popularity.
I would claim 'nice ux' is something that would not drive market adoption nearly as much as other factors (value, usability in general, etc).
I haven't played Pokemon Go, but it's fine for apps to use their own custom theme. What's not fine is to use one OS's theme on another OS, like an Android app on WP.
I see where you're coming from when you say that nice UX is not the most important thing, but a poor UX comes in the way of usability. The conventions users are used to no longer work, which comes in the way of using the app for its intended purpose. UI that doesn't fit might also cause users to pause and reorient themselves, again distracting them from their goal.
For example, wall switches in India are on when pressed downward, as opposed to upward in the US. Either works, but if the switches are different from room to room in your house, it's confusing.
If Microsoft is building a framework, I'd expect it to provide a great UX for their users.
If a compatibility layer is required, it would be better for MS users to have it in the reverse direction, to let WP apps run on Android, and use that to try to convince devs to build WP apps.
In summary, it never made sense for MS to provide WP users (their own platform!) with a second-rate UX.