This, to me, is the same problem with the paella.
The authentic real paella can only be made in a large flat pan, 1 inch deep, round rice, more rice than stuff, cooked without stirring in a fire pit stuffed with orange tree
wood.
If you try to make a customized paella you will get dire sights from the purists.
So, when we make a homemade paella we usually call it 'rice with stuff' to avoid infuriating the purists. (Still, we love very much the large pan and the no stirring rule).
A public park culturally has to be like the people there think it has to be. Maybe in a far past they tried many other things and that's what they ended up liking. The reason for keeping parks neat and clean is that many people dislike bugs, and mulch promotes living, that is, bugs.
The only way a see to bypass that cultural aversion is by not calling it a park. Maybe calling it 'bug city' is excessive. Perhaps 'wild park' or 'urban rewildering', something telling that you are not doing a conventional park, so yes, you already know that there are composting facilities, but this is not a park, so please, let us do it our way.