I think people need to play the campaign and relearn tactical game play, these people that just walk/run around the corners or wide open spaces and blame the game/lag seriously have forgotten how to play non 3 lane maps and need to relearn
The problem though is that there's a multitude of things all coming together to make it so bad.
-Mostly terrible maps
-Terrible spawns (no that this is new to CoD but coupled with the really shit maps it feels worse than usual)
-Terrible weapon balance (725 range, M4, Riot Shields, etc)
-Slower player movement speed
-Claymores being a very low level unlock, virtually everyone has two of them (there's not much competition for that perk slot which is a separate issue)
-Characters calling out shit where enemies can hear (how did this get past being a joke on paper???????)
-Loud as fuck footsteps (even after the most recent patch)
-TOO MANY possible sightlines
The last one is the biggest offender for me probably. At this point I know the maps well enough where outside of the occasional "oh I didn't know you could get up there or have that angle on that" I know where all the points I can be shot at are at any given location. The problem is that you can't realistically peek every window or opening because a lot of the time there's gonna be like 5 different angles you could be shot from. So when you factor in so many things that can one shot you with slower movement and having multiple claymores there's practically no reason not to hole up or play it slow. I make liberal use of molotovs and gas grenades for objectives, possible peek windows etc, but you can't carry enough smokes to realistically cover every movement you need to make. tl;dr the game makes you very vunerable almost always for any movement and everything is currently set up to reward camping up at a window, so there's no reason not to do that.
And yes, playing slower and more tactical works to some extent (most of the issues above still apply), but I don't think most people come to CoD for that experience. I have absolutely no issue with slower play and camping being made more viable than it has in the past, the issue is that they did a hard 180 from practically every one of the preceding ~10 games in terms of playstyle and what I think most people play and kind of expect. If I'd known it was going to be this much like this I honestly would have just picked up BF, R6, or almost anything else, because while the gunplay is great in this nothing else really supports this playstyle very well IMO. It feels like they didn't know what kind of game they wanted, or the game got focus tested too hard (or not enough) and I think unless they make significant changes pretty quickly this game is going to get dropped harder than any CoD has from a general population standpoint. Which is a shame because I think with some small changes they could at least make it significantly better, if not one of the best in years.