The cutscenes were going in the game either way as they were in the original screenplay and an integral part of the plot. So if we hadn't met the stretch goal it would have just been done with sprites in-engine (possibly with some closeups?) and done for the base amount of the Kickstarter goal. That's my guess, anyway.
Ultimately that would have been more Sierra-like, and probably would have kept the aesthetics more consistent. I can't help but think that such a thing would have been the better directorial call. Personally, I don't mind the cutscenes; I don't think they detract from the experience, really, but I totally understand why people have found them off-putting.