The problem imo is specifically that it's not just an init system. It's morphing into it's own thing that wants to take over all routine system behaviour, and the attitude of the devs is not encouraging (too lazy to find the link, but an oft quoted comment regarding log file corruption illustrates this quite well).
Linux (at least in my opinion) is all about choice. Don't like the way something works, use something else or write your own. Systemd is becoming a huge chunk that can't easily be swapped out for something else. I'm really against that.
And importance is relative. If you just want a functioning system, I agree that none of this is really that important and I'd probably just use ubuntu or mint or hell just windows or mac. I use gentoo specifically because I like my system "just so". Most people probably fall somewhere in between these points, with some past where they care about systemd and some not. I think this is perfectly healthy. If no one cared about init systems or boot loaders, no one would be developing them!