I'm less than eloquent, so I'm going to quote Ghaly's post from the official EU forums:
There seems to be a glaring problem with BM pets in wod. You removed all the CC and niche abilities like inturrupts from both exotic and non exotic pets in WOD which is understandable. However Now we are left with a two-tier system that comprises of:
Non exotic pets = 1 buff OR 1 ability.
Exotic pets = 1 buff, 1 ability (bloodlust, healing debuff etc)
It doesn't seem like something major to complain about and I understand its a proper first world problem. However what this does is limit beast mastery hunters to being stuck with exotic pets otherwise you are just gimping yourself by using a non exotic variant. This means that BM hunters will ironically only get to choose and use 22% of the families available to us (10/44) and have the least variety of pets of the three specs.
An example of this is wolves vs devilsaurs: Wolves bring a 5% crit buff. Devilsaurs bring a 5% crit buff and a -25% healing debuff on target.
Now while theres always 'just use what you want' the debuff in this example is really such a big deal (especially in pvp, but some pve soloing) that there really is no choice. The wolf gets stabled and we have to take the devilsaur.
Cast vs spirit beasts: Cats bering 3000 mastery, spirit beasts bring 3000 mastery and a significant sized heal on a 30 second cooldown.
Again, I love the cat models and this is one of the reasons I am making this post. Why on earth would I ever take the cat over the spirit beast? Being able to heal myself for about 20-25% of my hp every 30 seconds is way too good to ever pass up for a cat that does the same thing with no heal.
Spider vs silithid: Spider brings a slow, silithid brings a slow and a stamina buff.
And so on. We need some sort of system where BM hunters get a bonus ability from their spec for whatever family of pet they choose, rather than the pets themselves having the buffs. Or perhaps give all pets a second ability to remove the two-tier system and only allow the pets to use the second ability when the hunter is in BM spec. Something.
It used to be less of an issue because the niche abilities - like my gorillas inturrupt - actually gave alot of utility to choose from. Now that non-exotic pets no longer have any utility other than the buffs or singular ability they bring this means that non BM hunters basically get to use 78% of the pet families and looks, while the 'mastery over beasts' spec is limited to a mere 22%