Beast Mastery is currently is a good place right now but that isn't always the case each expansion. It seems like this talent tree gets revamped in some form or fashion each expansion.
First let's look at why BM is in a good place. BM is doing great because it now has all of the utility that the other specs had (Silencing Shot, Readiness, Wyvern Sting, etc) with the increased damage from pets (Stampede) and the mobility (BW stun breaker). A BM Hunter and his Pet can now do anything that the other spec can do (AoE, CC, DPS,) without having to consider changing specs regardless of PvP or PvE. You have accomplished your goal of not having one specific spec exclusively for PvE or PvP. It is too bad that BM is basically all three specs rolled into one spec but with a lower ceiling expertise. A turn-key spec. Hop on and go.
Many people enjoy the BM spec and I myself have played it for the last two expansions. This is not a cry for "nerfs". What I would be happy with is a clear definition of roles for each talent tree and to somehow reduce the number of keybinds and macro's needed to play the class.
Let's look at each specialization tree
Beast Mastery (BM)
Not really much to ask for in this tree. What I see here is an abundance of keybind/abilities bloat. I would like to see the following considered:
Focus Fire: Could we link this to Frenzy granting the hunter the haste buff until the frenzy effect wears off the pet? We could cap the haste at 20% and the focus gained to 3. This would free up a keybind that most hunter only consume after TBW.
Pet UI: Pet UI still seems wonky to me. The method of dismissing/rezzing/calling pets seems to be outdated for the Hunter in today's WoW. If people are still having problems (since Vanilla) with pet survivability why punish the hunter with a stationary cast time dismiss function? Either allow hunters to dismiss their dead pet while moving or simply allow the hunter to change pets like they would an aspect but with an implemented cool down system (suggestion 10 secs) so that a we can cycle Spirit Mend/Roar of Sacrifice etc.
The use of macro's for a bet to use their ability on other players also seems bloated/outdated. Could we maybe consider a pet focus target solution that would allow us to us our Helpful/Harmful pet spells?
Like I said not a lot of requested changes here. Mostly keybind bloat removal.
Why would anyone like to play this spec other than the play style alone? Marksman doesn't bring anything to the table other than pure ranged damage and currently a Beast Master or Survival Hunter of equal or lesser skill can fill that role. I have seen people request to make "X" passive ability MM only but to me that won't bring MM up, it will only bring the other trees down.
Mastery: Consider changing the Mastery of MM Hunters from the 80% damage autoshot proc to increasing the base damage on ranged attacks by a % or a % chance of allowing the use of Kill Shot/Chimera Shot after a successful crit (i.e. Warriors Sudden Death)
Readiness: Reduce the cooldown of Readiness from 5 mins to 3 mins for Marksman. 5 Mins feels too punishing for a specialization tree that is already susceptible to stuns/fears etc. With talents we can lower our deterrence and disengage cd's. Having a shorter cd on Readiness only increases our survivability and our ability to burst. With all the CC chains currently in the game our window's of opportunity close fast.
Rapid Fire: Lower the CD to 2 mins and extend the duration to 20 secs.
Master Marksman: Take the RNG out of this. Once the Hunter casts 4 steady shots in a 30 sec window he has the ability to fire an Aimed Shot with 0 cast time within the ext 10 secs.
Chimera Shot: Bake Widow Venom into this and remove it from the other Specializations. Let it be reapplied by a successful Chimera Shot.
This old tree has seen it's ups and downs over the years. From the Lacerate days to the 0/31/30 Hybrid days to the AOE/CC/Stun days. Survival always felt sort of forced and never had a real design until recently. Over the years many called for a Melee Spec while others thought that should follow the title of increased survivability. Without having to totally rework the specialization I think that we could stick with the Magic Damage dealer but focus on the survivability issue that hunters need in a bad way.
Black Arrow: First thing remove the shared CD with the traps. You can still make it able to be dispelled. This will actually make people think if they want to waste an 8 sec cd on this or not. Maybe consider adding a health returned portion from Black Arrow.
Improved Serpent Sting: If you don't like the suggestion of Widow Venom baked into Chimera Shot then consider the alternative to baking it into this and having it Mortal Strike the opponent as well as siphon health back to the Hunter. The amount of health returned is based off the Mastery.
Talent to be named later: In a future expansion/spell revision please consider giving SV the ability to remove dots.
Increased Stamina: Increase the hunter's stamina by 10% (see Prot Warriors)
Wrap it up with a nice bow
Some of these idea's/suggestions might be flawed. These are just a few things that I have been thinking about over time. To sum it all up I have always thought the Hunter Class should fit the mold of:
BM: Pet Damage Focused Class (Mix of Ranged/Melee Damage from Hunter and Pet)
MM: Ranged Damage Class (Ranged Hard Hitter on Single Targets)
SV: The AOE damage and CC and increased Survivability.
The Three trees would have 3 distinct play styles such as a Holy/Ret/Prot pally but all focused as a Damage Dealer.
That is how my conversation would go with a developer. How would yours go?
(There are no right or wrong answers. Please don't come in here and try to disprove people with your math or own theories. Share your theories and how they would enhance the Hunter class)