Bestial Wrath no longer grants Hunter pets immunity to crowd control effects, and instead now breaks existing crowd control effects when activated.
You forgot Bladestorm (and I am sure a few others). Don't thank me, I know how easy it is to miss things.
He is my reasons why this is not a good change.
1) BM Hunter without a pet is limited to Kill Shot, Arcane Shot, Cobra Shot, Serpent Sting, and (some) of the Talents as there primary damage dealing abilities. Our bread and butter ability (Kill Command) is not available if the Hunter is CC'ed (obviously), or if the Pet is CCed, or if the hunter is Disarmed. There are plenty of ways to limit BM Hunter damage significantly, and BW only breaks Hunter CC, there is no immunity.
2) BM Hunter's pet without the hunter is limited to Basic Attacks. That is it. Tenacity has a damaging move (Thunderstomp) that is an AOE move with inflated threat (read, less damage). Pet Family abilities are not damaging moves, except Worm/Chimera AOE, which can't be auto-cast. When a hunter pops BW, you can already drastically reduce the BW damage by CC'ing the hunter. You don't need a complete second set of diminishing returns (i.e. pet and hunter are counted separately) to CC the individual player.
3) You can't use the PVP trinket to break your pet out of CC
4) Glyphed Mend Pet (and not even the healing one) has a 50% chance pet tick to cleanse one debuff of each type. Rough estimates has ~33% of the time, you will lose over 50% of the BW duration before Glyphed Mend cleanses it. And that is if it cleanses the right debuff. And of course, if the pet is CCed again, 33% of the duration will expire before it ticks again.
5) Pet CC Immunity was not a problem, and if it was, then it should be just as big as a problem in other places. Pallies have their CC immunity when they pop a bubble (which lets them heal without hindrance, which is just as impactful as damaging without hindrance). Bladestorm has CC immunity (as alluded to above).
So, if you are going to go with this approach, then you should make a few additional changes to balance (empahasis) this out.
1) CCs on the pet count towards the hunter's diminishing returns, and vice-versa (same for any pet class to be honest, but the biggest issue pet focusing specs).
2) PVP trinkets (and similar effects) work on combat pets (not guardians, like Stampede, perma pets) as well as the hunter
Even then, this is not the way to nerf BM burst. You had the better idea making Rabid a Haste effect, instead of an AP one, and maybe adding a CD lockout between Stampede and BW (i.e. can't Stampede with BW active, can't BW with Stampede active).