Re: MPLAB X 5.30 appears to break its own make system under GNU/Linux for MPASMX projects.
The "install where you like" may also work for the linux distributions that are officially supported. If you take a look around at distros, you will find that there are many significant differences in how they are configured. It's routine to find software that will run in one distribution but not in others (and I mean, "run" as in "run at all") In some cases there is no fix (a certain other development environment with a license manager that simply refuses to run except under certain conditions comes to mind...)
We should always remember that, running in linux, we have freedom that is denied to Windows (or Mac) users, but with that freedom comes danger. Whether this is worth it to you is a personal question.