City and Arsenal already have tempo setting, sitting defensive AND attacking midfielders along with a host of recognised centre forward options. We have Bruno, who is a chance creation machine that spam balls literally left, right, centre that plays closer as a 2nd striker AND we have no centre forward.
Adding Mount would improve our attack but helps none of our issues like progressing the ball from the back or midfield control; it's asking an awful lot from him (who played with Kante, Kovacic and Jorginho to do those other midfield roles) and Casemiro to help tie it altogether.
Sometimes less is more. In theory (and at least the hope is that) by adding a player like Caicedo, our base would be so strong that it gives the rest of the team to push on i.e full backs that really go high and forward, which helps creates more overlaps AND helps your Rashford/Sanchos/Antony because there are more players to interplay. It also means they wouldn't need to keep an eye over their shoulder to track back, worrying about getting counter attacked because you have two really responsible and athletic midfielders covering. It means we actually have more players attacking in the opposition half. I'd be very worried about a front four (because that's what we essentially play as) of Rashford/CF/Antony and Bruno trying things and then seeing Mount in those same areas when we lose the ball.
As a single choice, Mount over Caicedo is such a risky move. If they came in tandem and/or we have other midfield targets, then fair enough but that's a whole different discussion. Also Caicedo is being severely underrated with his ability on the ball. It's the 'best' possible route for what we know of as of now and what we know of our current squad players.