The cookie-cutter spirit > mastery build just feels harder to top people up, the druid doesn't have a lot of burst on spread fights. Not everyone has the same strats/comps/playstyles, not everyone is gonna benefit from copying another player.
Well, spirit > mastery this tier has been replaced with, in ToT gear:
Spirit to 9-13k (w/ meta+horridon's) > Mastery > Haste to 25%* > Crit > more Spirit > more Haste
that's the current cookie cutter AFAIK. Nobody really differs that much from it if you really think about it. Except those who go crit>mastery.
*nearly unavoidable in ToT itemization, once you get close you might as well finish it
Mastery provides less front end burst but provides more back end burst reduction. But doesn't buff light's hammer.
On the previous page I explained why/when mastery is so good. Let's say you are getting 33% healing done on recount/WoL from mastery and you have 30% mastery. That means you did 66% raw effective healing without mastery and mastery boosted that healing by 50%. So for each %mastery you have you got a 1.66% increase in healing done per mastery. It takes 480 rating per 1.66% increase. Gaining addition will be subject to typical stat weight diminishing returns.
Crit takes 600 rating to per 1.00% increase. In addition to infusion of light. IoL is effectively a 1 sec cast time reduction after GCD, 1% crit provides 1 sec cast time reduction once every 600 seconds if you cast HS right on CD... for a 0.16% cast time reduction overall per 1% crit... roughly translated into haste that's worth about 70 haste rating. Subtract out the "70 haste rating" and you get 530 rating is a 1.00% increase pre-diminishing returns.
On overall meters mastery will typically win b/c overheal. In terms of raid burst (light's hammer!), that's not something I'm ready to comment on, it's tricky.
What I do know is that ilvl next tier will cause HPS to up another 30-40% next tier, while HP only goes up 15-20%... overheal numbers will only get bigger favoring Mastery. The EF HoT-mastery nerf though pushes things towards Crit. Therefore... people are largely ??? on 5.4 stats.