I believe and hope this will be an unprecedented opportunity to give balance druids a meaningful talent tree that is not a restoration's second cousin once removed
I'm proud of blizzard for being bold to do things like this and hope they really make the most of this for this spec. The debate they're having is whether to make moonkin form or starsurge the activation talent. I hope it is moonkin form because the form can be spec defining ability. Which is good and makes it necessary to be more important than it is now. That is do more than a mere 5% crit/haste.
Tbh, since the druid is a shapeshifter and our thing is shapeshifting as opposed to totems for shaman or pets for warlocks, shapeshift should mean more to a balance druid than a shadow priests shadow form or warlocks metamorphosis, and it should be interesting. As it was in previous builds, its boring and really only a cosmetic for the 3 passive buffs it yields.
How about a Moonkin form shapeshift mechanic modified slightly to reflects the nature/arcane balance of magic the form is centerd around now? Giving it an interesting dynamic that is more than a mere buff.
For e.g., shove the crit/haste or part of the ability you get when you pick up the form, but its available in any form. Freeing the form to mean something. For balance druids shifting becomes slightly different from shifting for feral druids or restos. It becomes something you do during combat. Give us a reason to move between caster form and moonkin form during combat.
An easy example is during the eclipses, during a lunar eclipse, damage in Moonkin form will be higher, and during a solar eclipse damage in caster form will be higher. Simple, it means balance druids use both forms, and outside and eclipse you can stay in the form you want. Adding some unique utilities that are very situational to moonkin form make it more meaningful. Make sure they're not rotation required abilities or that makes it compulsory to be in all the time like cat/bear form. Something light but useful in the right situation like a slow fall or a moonslide.
Now you have a dynamic form with some perks you can use when needed. if you don't like the form, you can minimize your time in it, only shifting for lunar eclipses, if you do you can stay mostly in it but you'll have to shift for solar eclipses. Druids shift, its part of the class, and for balance it is exciting.
Some extra incentives for caster form (or nature form) can exist too, and maybe moonkin form can have a trinket like feature, maybe Owlkin Frenzy turned into a 45 sec buff with 5 min cooldown during which a moonkin feels like the empowered caster it should have been all along casting spells like wrath/starfire/starsurge/starfall and cyclone better during that duration.
As you can tell this makes moonkin form not compulsory yet necessary, it makes it meaningfully as a spec defining feature and the way it operates reflects the specs theme portraying the balance between nature and arcane. It gets exciting and the empower ability, the owlkin frenzy stuff makes switching to the form have a powerful feel to it even though you may only use that empower frenzy once every x mins. Well there you have it.
May I just ask all you beta and forum posters this time to give quality feedback and your ideas in the forums, discuss this civilly without any whining, we have sometimes suffered from providing qulaity feedback by having our topics riddled with moans so they get ignored, quality feedback and ideas help make things happen faster.