Exactly, they made it totally unrealistic by trying to make it seem realistic. As for bitching and moaning, that is why I avoid CoD games. The whole series is so infamous for kiddies that rage and whine, that a "CoD kiddie" became a serious insult as of late.
Actually that give MW3 a purpose: keep CoD kiddies in MW3, so that the rest of us can play BF3 in peace 
Seem realistic? How can I fire a gun that is pointing straight but it hits a wall that is 3 feet to my left? It really doesn't make a lick of sense. I have actually never heard of Cod kiddies and I lol'ed when I said that out loud.
No, I definitely expect some of the CoD crowd to come over to BF3 initially because they don't want to feel "left out"... Sadly for you (I'm guessing you'll play BF3 on PC), you won't be seeing all of the CoD crowd rage quit when they can't run and gun effectively. As with myself, I will be "Owning my area" with an LMG and I'm sure I'm going to make a LOT of people angry. In all seriousness, the only thing that I will probably miss from CoD in BF3 is... actually no... BF3 will be just better in every regard. I mean, the game looks better... it has big open maps... vehicles (trust me people, vehicles are damn awesome and made Battlefield into what it is today)...
I will say this for everyone to hear: CoD is like Pamela Anderson.... they both use a lot of botox and you die a little bit each time you enjoy them. Battlefield 3 is like Demi Lovato... they are both very good looking and will probably make a lot of people blow their loads prematurely... I for one am a very seasoned 1942/BF2 operator... and I may like looking at Demi sometimes in my free time.

(You can thank me later)