This is "version masturbation." There seem to be lots of people who all they do is upgrade their computer all the time. Then they are somewhat unhappy when a new version comes out once every few years rather than once every few months or days. If you don't actually use your computer, then yes, upgrading every few months is fine. If all you use your computer for is browsing porn, then yes, it is fine. But if you really don't care what version you have, you just want it to keep working, then this is nonsense.
Did anyone notice that Win XP is still very popular, and not just among businesses. Still it is the most used system. Why? Because why change if it works. The problem with upgrading is that it will inevitably lead to something breaking. If the computer is a tool, you don't want it to update automatically all the time.
Why is TeX/LaTeX still heavily used (e.g. in Physics, CS and Math community, the community it was intended for). It is not because a new version comes out every year. In fact, a new major version has really not come out in 17 years. Nobody is complaining. There is a LaTeX3 project, but it has been around for more than 20 years. A new version is not likely to come out. OK, some new macros have appeared in the meantime, but you don't have to use them. In fact, I know someone who still uses plain TeX to write papers (and uses unix "mail"), and is very productive with them (I have gotten him to use LaTeX for some of our collaborations though, and he does sometimes start "pine" for mail to send/receive an attachment).
But TeX/LaTeX is used by the scientific community that uses it as a tool. If a new version comes out, it will be years before it would get adopted.
The upside of updating to new firefox is minimal. Actually one can't really see much of a difference over all the firefox versions really. There are very few websites that won't work even with very old firefox. The downside is work interruption.