I mean I’m not entirely in disagreement with your original statement. I don’t imagine they change much about their gunplay at all, apart from adding some new mechanics each game, and they likely crank the core out quickly by either reverse engineering, refactoring or just copying the whole thing in.

My main point is just that the “coat of paint” which they do indeed throw over reused mechanics probably takes a whole lot of work. It’s perhaps lazy thinking, but not lazy design exactly.