Too much of my PvP damage is from IS/MF when all I want to do is have other spells be viable to cast. WM is just another abliity for the Druid that doesn't click with the Balance Druid as a whole, but just adds to the variety of random, non-interactive, discrete abilities and effects we have.
In PvE we have Eclipse; in PvP we don't. Does the Balance Druid have enough functionality to be viable all types of PvP at lvl85? If not, is WM where we can finally have our ability that people go "oh no, he's really good with his WM!"?
I believe making WM instant would go a long way to improving their functionality, as well as giving the Balance Druid something to cast in PvP other than IS and MF spam.
Secondly, are they viable/useful for any spec without Fungal Growth? I don't see that they are unless there are changes coming to allow detonation in Feral forms (as has been suggested as a use). This would then beg the question as to whether WM is more useful to a Bear than a Moonkin.
Simply making WM instant cast (even if only for Balance or via a glyph) would instantly make WM a viable option and something you would want to cast, even if only for FG if WM's damage remains not the focus (ie. low).
While I don't feel it's interesting as a part of our standard dps rotation, as OP mentions, the cast time is unnecessarily prohibitive anyway, and I would much rather have WM-while-moving than have it decided that I have to spam MF.
On a note about FG, we already have enough ways to keep players away from us (Typhoon, Roots, Travel form, MF spam while moving), but we have little to do once a melee (player or npc) is on us. Do we need a snare? Or is there something else that would benefit us more that doesn't have crazy implications for PvE?
If not instant, than WM could potentially even be a channelled spell with more WM summoned the longer its channelled. Castable while moving would still allow us to then have something other than IS/MF spam in PvP, but then there would be issues of range and a ground-targeted cast-while-moving spell as well as also then giving us another spell to be interrupted in PvP.
Even a Typhoon-esque ground-smear spell that randomly plants several WM, waiting to be detonated? I very much like the area control that Balance Druids are trying to have, but I feel they just don't have any "Balance Druids strengths are this" traits that we can learn to be skillful at.
Basically, there is no depth to Moonkin PvP and WM is the wild card we have left to add to, assuming they're actually castable (instant). I feel there are too many Balance mechanics that are held back in potential, which gives us an arsenal of noncohesive, 'not-quite' abilities. I'm sick of MF spam being our most viable method of PvP damage.