I think what a lot of these adaptations fuck up (and this applies not just to those of Jap IPs), is they try to tell one of the big grander stories of the franchise to be a big spectacle and draw people in. Something that in the original was an entire season or more, which they then boil down to a single 2 hour or less movie.

Transformers for example is about to try and adapt Beast Wars in a single movie, because it has the biggest fanbase after G1 of the franchise, and its going to work against it.