By the time this movie comes out, we'll have been 7 years since the last Avengers movie of any kind. That is longer than any other point in the MCU in the last 18 years when this is released, average was 3 years previously. So how long are you expecting them to go before we have another Avengers event level movie? How long do they need to build it up in order to get to that level? 10 years?
I understand it may not seem like it, but they were building toward something previously. They've had to pivot because of issues beyond their control and are now trying to get back on track. So it may seem rushed in terms of story arc, but Mutants (X-Men) was always the goal of the end of this Saga. Its why they've teased it previously with the Ms Marvel show and the Marvels movie. We're 2 years away from the end of this Saga and barely scratched the surface of that. And if you know the comics and the story they appear to be telling, this question is sorted of answered on why it seems they are dependent on the pre-MCU stuff. In my opinion Battle World is likely coming and an eventual reset of the MCU, with the eventual Avengers vs Mutants storyline taking over.