One of the main reasons to use h-feed and h-entry is that RSS/Atom really only can represent blog posts and podcasts. For those purposes, they're fine formats, but the reality is there are many more kinds of content on the social web today, such as replies like this one which can't really be represented in RSS.
What features are you finding that Microsub doesn't support? Like most of the IndieWeb protocols, Microsub is supposed to be an evolving protocol based on the needs and implementations of people using it. I don't expect that we will ever say "Microsub is done!" the way that some specs put a stick in the ground, since the reality is that things change and need to adapt to new use cases to remain relevant.