battletech was also launced without the option to skip/speed up animations.
Both games are Unity, probably it has something to do with it.
It really, really doesn't - as someone with 10+ years of experience in programming (including some game engines, including Unity) please believe me when I say:
That is a problem of code structure/design.
If you didn't plan for speeding up combat to begin with, and you didn't decouple animation logic from actual game logic as you should have, it would always be a lot of work to alter it after the fact.
When things go really spaghetti-code (and with lots of game devs, that's honestly what I've come to expect) there might even be a giant tail of code that depends on animations actually playing out "nicely" so that other things work right, so then you'd have to change the animation code and all the things that depended on that and... if that sounds annoying, that's because it is.
I'm facing similar kinds of problems in lots of projects I work on - a lack of foresight that lead to an absolute mess, costing days or weeks to fix...
Anyway, point is that this is a certain kind of incompetence that is independent of any used programming tool and not even purely related to games.
What is so insane about it to me is that every single player of turn-based games knows that these games NEED a way to speed up combat. And yet, here we are.