@baldur Have you looked into using alternative apps for posting? I really don't like writing anything in the posting UI if I can help it (so only use it for replies like this), but there are some great third-party apps that can be used to post.
Paper's free version is very generous, and can post files as drafts to Micro.blog. Personally I use Ulysses, which is awesome. (Through Setapp, so I don't pay more for it.) It supports keywords, scheduling and everything. I use the Inbox in the app for micro.posts - so that makes it super fast to post those. I think iA Writer and MarsEdit is supposed to be good as well.
Is it optimal that you need something else (maybe not even free) to get a good posting experience? Absolutely not. But you at least can get a very good one.
(I to disagree with a bunch of the priorities at Micro.blog, sadly. =/ But I do really like it as a place to host my blog, with some minor social media-ing on the side.) @Denny