Spells don't get nerfed arbitrarily; and rather than complaining about a nerf I think it's more useful to try to deduce why the nerf is being implemented, using the mechanical changes as evidence of the implied intent. Only after the mechanics of our entire spell kit are analyzed and adjusted can we even begin to discuss the issue of throughput which is always the last question to be answered (and even then we must discuss total throughput, not each individual spell's throughput).
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I would make the following three observations and deduce the respective conclusions from them:
1)
WM's spread potential has been removed
- (from this I would deduce that the devs felt WM's spread potential was too strong, and/or it was being abused, and/or we already were capable of spread healing without WM so it was redundent.)
2)
WM's burst healing has been reduced, and in particular its burst+spread potential has been removed; but a new mechanic has been added [Genesis], which can be used as a burst+spread mechanic by synergizing with one of our traditional spread mechanics [Rejuvenation].
- (from this I would deduce that the devs still want us to be able to burst+spread, but they don't want us to use WM to do it, and they want us to be able to do it within the limitations of our mana and in keeping the traditional design of our class).
- @Insanedruid, you say Rejuvenation+Genesis is not better than the current version of WM, but i would counter by saying there is no need for it to be BETTER per se, it merely needs to be sufficient to purpose for which it meant to be used. Genesis is like Uplift on a Mistweaver, only we can control which targets are affected by rejuvenation (unlike Renewing Mist) at the cost of more GCDs per minute and the resource cost equations are of course different.
3)
WM's mechanical placement has been significantly altered, and in particular it has been simplified
- (from this I would deduce that the devs felt that the current placement mechanic is too challenging or awkward, and so have decided to simplify its use, leading to more reliable placement and use.)
- @Insanedruid, you say that in mobile fights where the the raid is spread out, being able to move the mushroom doesn't help much; and in stacking fights you know where the raid will be, so being able to move the mushroom, again, doesn't help much. But I would counter by saying the intention appears to be that Rejuvenation+Gensis is the mechanic you use on spread and/or mobile fights, not mushrooms at all; and what the ability to re-place mushroom without loosing the bonus healing really does is reduce the punishment for imperfect play. Basically, i recognize that in a perfect stacking scenario you know where the raid will stand, but in real life how often does a raid group play perfectly?
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With regard to points 1) and 2), I personally feel that druids have been known for many expansions to be superior spread healers based on the strength of rejuvenation, wild growth and tranquility. When Wild Mushrooms was added it gave us another tool to solve a problem we were already fairly capable of solving. What the devs have done is removed the redundent tool and shifted its healing potential back onto our traditional tool by way of Genesis. This seems like a reasonable change, from a mechanical point of view.
With regard to point 3). I personally despise the current mechanics of wild mushroom because I hate ground targeting reticules. They just get in the way of a healer's ability to use mouseover macros and/or healing addons when we are trying to maintain 'Always Be Casting'. (I also hate Healing Sphere on my Mistweaver). I grant that WM heals really well, but the mechanics of the spell are clunky as shit. It's a total pain in the ass to ground target and cast heals at the same time; plus if i have to relocate the mushrooms, or if my team members move, all the bonus healing is lost. The current spell is, in my humble opinion, horrible, from a mechanical point of view. Having played on the PTR, the new mechanic is so much easier to use that I have no problem fitting it into my rotation and I know that I can pre-load the mushroom and place it where i need to place it and never have to use a goddamn ground targeting reticule again. People who say the PTR version is clunky but that the current version is not clunky are speaking gibberish.
I don't really care if WM has been nerfed based on its healing throughput, the fact is
it has been buffed in terms of its ease of use and if our ultimate whole-package throughput is insufficient, then our healing (perhaps in another spell) will most likely be increased to compensate.