It's easy in comparison to making an entirely new combat system & ai behaviour trees, whilst also planning a game direction. I never said it was "me press button, me get animation" it still takes time, plus it seems Kvento wants to integrate the animations into scenes triggered by certain conditions, which would requires conditions which don't exist yet.
Please give game dev a go before whining; this is nothing compared to the delays Animo super-imposes after giving false release dates.
Yeah man, just trust the dev that's been working on a beyond glorified proof of concept for 4 years that's barely had any content added throughout its entire lifespan and sat at an overpriced access pricing tier, all with absolutely nothing to show for it, and then gut it to do it all over again. He's totally not milking his supporters and wasting everyone's time to keep getting paid.
Also this dev has given false release dates in the past, so your Animo comparison falls flat (especially when Animo's putting out better content).
Here's the fun thing about people who know how game development works and people who don't, the former knows when a game gets gut for a rework it's to stall while the latter thinks it's a necessary step in reworking the game.
It's not necessary or even suggested unless you're explicitly doing something like changing fundamental gameplay aspects in a wildly different direction, something where the existing code is literally unusable for the gameplay's functionality, which we know isn't happening here because he's just taking the existing system and tacking more stuff onto it (looking at the code, Kvento's barely done anything at all to it).
You can rework your game from the codebase up without scrapping everything, in fact, doing that just makes your own job harder and take muuuuch longer. And considering the old 'game' was fundamentally just a dev room to test animations and assets, there's no reason to not keep it implemented beyond wanting to drip feed the same content back to supporters.