This is a terrible attitude towards code you support for a number of years. It seems like you just get to dump on the next person, so I guess it works for you, but if one of my people sent a hatchet job in for code review they can expect to get an earful until they do it right.
Knowing that refactoring for developer ergonomics isn't the first priority of every project is important, I think. If I was working for you I'm sure you'd argue with the C-level well enough to give me the time to write tests that run in isolation, which would give you enough time to give me an earful if I didn't!
I think it's good to prevent my test suite from becoming unintentionally stateful. People come and go from projects and you have to keep on top of security updates, so being strict about how things are done makes the project easier to manage in the long run.
