I don't hate m4. Could be worse, could be better.
I used to build websites using m4 back in the 90s. Back when static site generats were popular, before the latest slight resurgence.
To misquote Mitch Hedberg: People either love it or hate it, or they think it's ok.
It looks like if you dive head first into learning autotools, then m4 is going to look like nuisance.
But if you allocate time to learn m4 for what it is, instead of just something you have to put up with as part of your autotools adventure, then you'll hate m4.
m4 is the only (or one of a very few) well-known general-purpose language-agnostic macro processor I know of.