I completely agree with you and am blatantly piggybacking on your post :O

But you're still right! :P

One thing that I'd like to point out about Improved Mend Pet: This is an extremely good talent in PvP. With Revive Pet as a 10 second cast, getting our pet going again is close to impossible in an arena match. IMP removes most DoTs from our pets, which greatly decreases the damage that they take. I'd be very sad to see it go.

I do very little raiding and a lot of PvP, so I'll chime in some more PvP oriented changes:

1. Give The Beast Within snare and root immunity. In Wrath we had complete CC immunity under TBW. I don't think this is too much to ask.
2. Cause Kindred Spirits (or Spirit Bond) to apply the PvP Trinket effect to your pet as well. Cunning pets have a PvP trinket talent (and I have that talent macro'd in with my trinket), but it'd be a nice thing for BM to have since a lot of our damage is from our pet.
3. Increase the range of Kill Command or make it function like Intimidate (Intimidate, for those that don't know, gives your pet a buff that fires the actual stun/threat on its next melee swing)

That's all for now.

Yeah, Beast Mastery wouldn't be bad and I assume would in the end be less "powerful" (thinking lowbie PvP here) than BW, but there's not many exotic pets 'til around the 40's if I remember right.
There's that rare worm in Dustwallow and some worms in Desolace (though with the redo there I'm not sure if there's any reason for a lowbie to step foot in outside Mara any more) and some wyverns maybe in Stonetalon, but then that got a remake too so again not sure if they're still there.
I'd love Beast Mastery for lowbies since BM is really focused on knowing your pets, but unless they add some lower level exotics it'd be about as used as Intimidation.

@ Scunosi there are worms in Ragefire Chasm, Chimeras in Azshara and a core hound in Azuremyst isle. Devilsaurs are available at 54 from Un'goro, and the lowest level Silithid is 32. The other exotic species aren't encountered until after 69, but Five options is pretty good. The one caveat here is that taming the Kurken at 12 would give Bloodism ridiculously early.

They could easily make it so that you can tame these beasts at any level, but, to use the Kurken example, make it so he doesn't learn his special ability until level 69 or something like that. A lot of pets have, or at least used to have (maybe this changed in 4.0) abilities they don't have at low level but gain as they level up, although I notice this mostly on my warlock as you often learn to summon these minions well before they're high enough level to use some of their abilities. Exotic beasts could easily work the same way.