There are ways to add your own CSS file to Joplin that should help manipulate the visual aspect of the headings in a more desirable way.
You can find more about Custom CSS which should be able to do what you want on your own (if you desire), see Introduction to customising Joplin. There is also Editor Themes plugin if you want to stay in the markdown world and have some more options.
I can definitely understand why you may want more distinction as well. It's probably mostly a personal preference as a whole. I mostly live in the markdown side of it and prefer the blandness of it and only switch when I'm going over something with someone.