Can't say anything about the hit detection as it's the best since MW2. Camping in any modern FPS will be prevalent due to the nature of the players. When you make games that appeal to 12 year olds with ADD and a general sense of laziness, guess how they're going to net their kills. Running around and playing aggressively doesn't appeal to those kids. It's fun for them to lay prone in a bush, kinda like how they veg around all day (explains childhood obesity as well).
I do agree that there are tons of idiot crap talkers online nowadays. You should just ignore them as most are trash players and the majority of players are better humans than that.
Aim assist if brought back will just means people will die that much faster. Having a 1.15 k/d isn't bad at all. Just because you don't do nearly as well in this game doesn't mean it sucks. I am not a camper (and many here who I have played with will agree), I run A LOT and consistently have games 2+ k/d in deathmatch modes. Most of it is knowing where the campers like to hide and you will find that most people hide in the same areas every single match. Also knowing the maps intimately will help you maneuver and pick up sneaky kills which often make people go WTF?! Yes, there are those rage games where a guy will be ADS'ing with a thermal LMG, but whatever, let them get their 10 kills. They often don't talk much when someone goes off for 30+ kills on them and quietly leave.
The game is not perfect, but far from unplayable. TBH, aside from MW2, this is the funnest CoD to date as it truly focuses on gunplay. Nerfed killstreaks mean campers often will not be able to do much even if they get them. And my best games usually result from running 5-7-9 as my streaks. Anything higher isn't as effective as getting gun kills is faster than many of the higher level streaks.