You keep saying with futuristic you can innovate, R6S stuck with the contemporary setting and it managed to innovate.So become Battlefield? How is that innovation? That's the death of it. At that point, it would become: "Do you want a lot of players or small players?" Why make Call of Duty, Battlefield-lite.
That' honestly way more subjective than anything else. Siege feels like that because the game is supposed to be tactical, it's not supposed to feel lighter and swifter. The rappel mechanic for example, works because of the slow nature of the game.
Again, though, all your suggestions are just taking shit from other stuff. At least with Future stuff, they can create game mechanics they can't actually do in modern times or in the past without becoming other game series.
And Call of Duty can use things like rapelling and wall breaches while keeping the fast pace, and just because it borrows things from other games doesn't mean it can't improve upon and refine them further, make them fit with the fast pace style of Call of Duty.