[aaravchen]

You can install whatever shell you want on your system, and there are tons of better alternatives out there. Where it's actually sticky is in the lowest-common-denominator cases, when you need to throw together a quick series of commands that need to be run on a semi-arbitrary system. In that case there are VERY few options because you have to use whatever is already on the system. Sometimes you're lucky enough you can safely assume bash is present, but in many cases you have to assume only sh. Unfortunately both are a difficult/footgun enough language that it greatly helps to start out using it daily to get familiar, and that's where most people end up peaking. Additionally you may need to manually jump into that semi-arbitrary system and do things manually. You're limited by the minimal tools already there, so you better be familiar enough with them already. This is the very reason I've learned some basic Vi commands as well, even though I would never even consider using it otherwise.

In my experience Power shell is actually a terrible replacement because you have to learn not only every command, but the structured return and available input formats of every command in order to do anything. The design of almost all shells is specifically to avoid that and reduce to a common universal input/output format. Powershell could certainly be useful as an intermediate choice between a full blown language and shell scripting though, if you needed more power but not so much to make it worth the load of a real language, but would also require it to be ubiquitous already (which it's not).