I agree with this point, check corners etc. But some of these maps (Tremor, Freight, Sovereign in particular) are just a nightmare to navigate. There are way too many places you have to look before you come around a corner. Freight is the absolute worst map I've ever played on any COD. I am constantly getting shot in the back on these maps because there are just way to many passages and lines of site to cover before making a move. The maps I listed above don't have any good ways to play them. If you move too slow, you get shot in the back. Move too fast you can't get your gun up in time and die that way. Sit in a corner and you're labeled a camper. Nobody wants to be labeled a camper because we all know campers are the biggest ******* in online gaming.
As for play style. I've adjusted. I was always a run and gun type of player, but now I take things a little slower. I still stay on the move the whole game, but I sprint less and ADS more around corners.
While I agree with most of what you said, there will always be people camping no matter how big or small the map. I've seen people who just lay prone on their spawn the whole game getting 1 or 2 kills. For them, that is how they have fun in COD. So I never complain about camping because it is a total legit style of playing which a lot of people prefer.