Very true. My biggest concern, I think, is memory - have a few VMs running on this thing and I think things are starting to get a little cramped. All-in-all though I'm impressed how well this thing's holding up to what I've thrown at it...
Yeah -- my Mac Mini 2018 does so much with so little its really hard to justify replacing it at all. I know the new ones are faster, etc, etc, but short of playing with local AI, etc, there's not much its hardware can't do that I need. The software support will end before its usefulness does.
A Mac Mini M4 w/32GB of RAM is only $1K in the US store, which I think is still pretty reasonable. Still 1/2 price of a Studio for probably similar performance and almost the same life expectancy for the previous things you've mentioned.
The Studio makes more sense to me when you need to go to 48GB+ RAM, want TB5, benefit from the extra GPU, encode a lot of H.264/H.265/ProRes videos, or do long-running calculations. Short of those things, the base M4 (with up to 32GB RAM as needed) can handle a lot. On the other hand, if your needs are such that a spec'd out Mac Mini M4 Pro is the lowest you can go, I would jump up to the Studio for a few dollars more.