I'm currently writing a Joplin Notes article series gulinux.ch about Joplin. And in the comments on Mastodon and under the articles, this is a common question or criticism.
I understand that due to the Markdown formatting, handwritten recognition is not or not easy to implement, but from my point of view, this is actually one of the biggest points why people are hesitant to switch or not completely satisfied.
We also have a teacher column on gnulinux.ch. Among other things, they write about switching to Joplin and Xournal++. They partly export from Xournal++ to Joplin. If there could be a better integration, it would certainly be a big plus.
Maybe @laurent can comment on the technical challenge and feasibility?