I don't think that's a bad thing. A big part of effective software development is building things in a way they can be re-used, then adapting that re-use to your use case. You don't want to re-invent the wheel every time.
With UX specifically, user expectations also play a bigger role, and you need to be careful with how and when you violate expectations. There's a reason most FPS games have settled on the same control scheme. Unless you have a very good reason for a change, it detracts from the user experience instead of improving it.
There are issues with the fact that the games are done so fast that none really have their own soul, but shared core UX (that's pretty comparable to most other similar games) is reasonable. It's the fact that it's not as good as it should be (mostly by shoe-horning in all the ads for shitty monetization) that's the issue.