Trap being instant, as a guy who has mained hunter for 3 years, is BAD.
It only makes it faceroll for hunters who don't know how to properly scatter trap, but I can tell you that putting off a scatter, then shooting off the "instant" trap right away, is gonna lose 2 sec off the scatter.
Now on the other hand, having the freeze trap like on retail, to activate upon 1.5 second, is much better, because you get no downtime. You get the full duration of scatter (almost) and you then get the full freeze. 3s+8s = 11s (Otherwise 1s+8s=9s cause the trap is instant)
Chimera is working as supposed.
So are pets, when you dismiss a pet, it will always reset its cooldowns no matter how many times you dismiss it. And unless you really suck, the hunter you're playing against wont be dismissing pets like you guys are saying, besides in the occasional deterrence.