I've talked about it with some people though, and we kind of agreed that a notable downside of it is how it makes soil quality - something that has always been very coveted and valuable in the game - kind of useless now. This is partially nice because we needed a way to "grind" soil quality for the end game but considering how fast we can get the first and fastest crops (like carrots) to q40+, I'd guess that even in a new world we'd have Mulch of higher quality than the best soil nodes (q40+) in a couple of weeks or less.
So, thinking about ways to make soil quality important again, I came up with an idea that might be interesting; that's up to you, of course

It obviously makes things more difficult

The idea is:
it's not unusual to add garden soil or fertilizer soils (like NPK) to composting bins to accelerate composting or increase its efficiency.
So, what if instead of just "creating" Mulch from produce (quality based on the produce and softcapped by the bin's quality - how it works now) it rather "transformed" units of soil into Mulch with said produce? So you have to fill the bin with soil and it would now cap the Mulch quality (based on the produce) on both the bin AND the Soil provided.
That way, good quality soil will always be a valuable good since it will allow you to have a lesser softcap on Mulch quality.
An alternative would be:
instead of "transforming" soil into mulch, to have a second "fuel bar" for the soil so the proportion is higher than 1:1. For example, 1 unit of soil will allow 10 mulch to be created. Since one of the ideas of the composting bin is also removing the (annoying) need to dig for soil all the time as well.
Perhaps it could even function without soil at all (like now) but then it would softcap the mulch as if normal (q10) soil was used.
Anyway, these are just a couple of thoughts on Mulch's awesomeness and how it could keep being awesome but also give back some value to soil quality nodes in a next world.
Thanks for reading and please feel free to criticize
