I would primarily like to focus on the mechanics and play-style involved with the spell Wild Mushroom and Wild Mushroom: Detonate. It's already painfully obvious that balance druid sustained AE for situations where hurricane is the appropriate spell is very low and balance is on the bottom of the AE class spectrum.
Currently the appropriate thing to do in a situation where multiple mobs are clumped together is use hurricane. It's a rather bland spell that functions the same as non-destro rain of fire and blizzard. Simply select an area on the ground that you hope mobs will stay in and channel for 8 seconds (now is an appropriate time to alt-tab to find an enjoyable song to play before placing the next hurricane) rinse and repeat. One spell, one interaction with WoW every 8 seconds. Forgive me if I fall asleep playing a moonkin. Besides being boring this also has risks with mobs being to spread out, moving, and it doesn't have a really huge payoff in comparison to single target damage abilities.
I am comparing this to an accepted playstyle in Cataclysm for Balance druid AE. Previously moonkins would enter solar eclipse and roll out sunfires if adds are spread, followed by a mushroom detonate when they are clumped. Place mushrooms once again and get sunfires out on high hp mobs or typhoon/hurricane low hp mobs. This is around 5 spells to cast during aoe compared to the single spell in MoP. Spamming mushrooms didn't limit my movement completely, as aoe does in MoP. Mushrooms had a sort of build up time because 3 had to be placed and a cooldown, but aoe was "worth it" for a lack of better words in Cata and I never wondered if I should just single target when AE damage was appropriate.
Basically, I don't like hurricane. It's boring, it completely restricts my movement and the movement of the mobs I am damaging. It should be more situational now, as it was last expansion. AE spells in general should be more situational rather than spamming one spell such as hurricane for 30seconds (cough chain lightning, mind sear etc). I think bringing Wild Mushrooms back into the aoe rotation by just by buffing their damage to a point where the DPET is greater than hurricane would be amazing. It's become so dynamic and fun for resto druids, but remains untouched for balance. I like the idea of charging something up, then blowing it up, which is how I feel mushrooms should function more for the balance spec. I like the feel of using mushrooms, but unfortunately on most fights I can only use them once (preplacement).
I don't think the proposed glyph will be incredibly helpful. Just from looking at the tooltip it appears now that it would be worth it to place a shroom, detonate it, then hurricane while waiting for the mushroom cooldown. The primary problem is using hurricane for more than a full channel. Balance druid will still be substantially lower than other classes for aoe damage, without significant raid utility or another damage niche to counterbalance the weakness.