thanks, @chrillek .
first, your post reads like addressed equally to DT-team (who actually introduced WYSIWYG as term, even in UI) as to me.
saying that bec I want to talk about substance, and too often these discussions here are derailed by slight ad personam drifts.
also saying this, bec I agree large parts.
I also would prefer to talk about a ‘modern MD-editor’, especially as relates to its functioning in the DT-environment.
but then, there is no shortage in the forum about (me or others) having raised concrete points of improvement. and often you were present for those discussions, I remember. but in my long experience (almost) any proposition raised was mostly matched by a ‘principled answer’ or ‘stance’: either along the lines ‘it works for me’, ‘this is the way an MD editor should function’, ‘DT is not a notetaker’, ‘go look for external editors, if you want (x)’ with x = anything.
happy if you point me to discussions that have escaped this ‘generalization’/‘totalization’/‘personalization’ bias.
in that light, the current improvements were a pleasant surprise to me, esp as these things never seemed to have registered in the many different forum discussions (as to my impression)
then, deeply agreeing with your (hinted) sentiment that improvements are (should be) – of course – about functionality as about UX (actually this is not mutually exclusive, anyways)
so, as to the new improved editor, as I already said, my (very personal) expectation would be that a WYSIWYG, ‘modern’, ‘adequate’ whatever quality includes:
- hiding/ separate coloring of markup
- separate font-setting for headings
and, I would add now, as little luxury 
3) being able to define paragraph spacing.
– all that as part of the ‘editing – = writing – experience’, which is basically what these discussions are really about.
(also, the OP mentioned toggling headings, which I think is ‘super luxury’
)
I also pointed to the Ulysses editor-theming…
so, would be happy if, finally, things like this are discussed in a concrete, open, non-dualistic, and non escalating/disparraging way… 
let’s see.
PS-edit @chrillek: – on a personal / terminological note: there is the ‘extended sense’ of WYSIWYG ‘metaphorically’ blending the old type-oriented scenario to the digital interface–and-document-scenario. and as language and terms ‘live’ a lot of people (and actually ‘experts’, resp established industry players) are using the term in an extended sense now.
Wikipedia:
Blockquote
WYSIWYG implies a user interface that allows the user to view something very similar to the result while the document is being created.
– actually, you yourself sometimes seem to use it like this.
Generally, though, I think such ‘labeling’ discussions are a good example of getting sidetracked in relation to obvious proposals/requests as to improvements in UX in editing + writing.