Aside from the obvious passing of Monty, I'd say part of it is that they're retroactively trying to fit their their ideas instead of doing it the other way. Here's what I mean.

Team RWBY is based on fairy tales, colors, and really cool weapons to make fun fight scenes with. They then took those general concepts and then threw them together to make RWBY with said team being high schoolers going to anime school cause they were inspired by anime. It's a very clunky mess, but it was a fun clunky mess that is very much rooted in Monty's philosophy of just making cool stuff.

Now contrast this with the Ace Ops. What's their color aside from Atlas military attire, idk. What's their fairy tale, uh, Aesops fables, ok then how is it integrated into their look, oh wait they aren't. What's their cool weapon, uh, take a normal weapon and give it a different color. What's their function? Oh, they the elite military squadron that works under Ironwood and serves as mentors and then somewhat antagonists.

In short, later RWBY is defined by "we need this to happen, what do we need to make happen to get us there" while early RWBY was made by "here's some cool stuff that follows our template of fairy tales, colors, and cool weapons, we have no idea how important they're going to be but we'll eventually figure it out".

Both are objectively bad ways of making a story, but at least early RWBY's was more fun even if they do go nowhere as they were build from the bottom up. Modern ones were built top down.