Where is the sense... ?

Just watched this video of Crysis multiplayer:

And don't get me wrong.. it is great game and all.... just wanted to bring ur attention to some annoying things here...

I mean yes it beta and all that, but there are few things I hope they will sorta make sense of before releasing...
when you get about 2.40 into the video the guy there shoots the tires of a car, which.. you know - why not, but then they simply explode!! wtf!! I could see it being a case in moving car, but if it is standing still? oh common.... and it does not end there either.... He goes on to shoot up some non flying chickens... or whatever they are supposed to be... uses same gun... but when shot they just lay down!! i mean common.. it ain't a tranquilizer... the blast should blow them away or like the tires blow up.. but no. They just like fall asleep and that is all... at least there are some feathers at the end.. :D
and just out of random... why would you go on rampage to kill chickens? are they really that annoying??