don't think they are "taking the lion's share"--if that where the case, people wouldn't be getting great xp on the more durable, heavier hitting jobs, or on the lighterweight jobs if they change up their playstyle--even with the presence of SMN's in the reives.
SMN isn't simply preventing a bunch of other jobs from getting decent rewards...they may reduce one's potential rewards from
curing only if they don't adapt and compensate for the competition, but that's not just SMN that can do that--it could just as easily been a group of people on the same jobs that simply came into direct competition for that one player's slice of the action. So, technically everyone may get a reduction simply because someone else steps in...that's not because it was job x, y , or z...it's because another player is also doing what you were relying solely on for your rewards. That's the problem with putting all your eggs in one basket.
There is a flip side to this as well. It creates the possibility of enhancing everyone else's rewards, simply by the virtue of increasing efficiency. If people would really analyze this, they might find that by having other people assisting like this (whether its a couple SMN's or a band of happy WHM's), it frees people up to do other things they otherwise might not be able to, because they're stuck solely on that one detail--that could be any support capacity...haste/refresh cycles, curing, stunning--the point is you have less pressure to do this one thing, freeing you up to expand your contribution to the group.
There are other things that can be done for credit in reives, just like there was in all the other similar events that came before it. If you are letting yourself get pigeonholed as a one-trick pony, this is potentially going to happen to you in
any event like this. All it takes is someone else stepping in to do what you are doing, regardless of the job--it can even be the same main job, but a different subjob, or simply different gearing that is allowing them to out-perform you in some way, and your usefulness gets diminished. This is true for a tank, a DD, a healer, a kiter--any job can be affected in this way.
We've seen this same type of disparity amongst players with all those other events in the past. For whatever reason, people figured out they couldn't turn big numbers doing things the way they expected to on a given job, so they figured out a better way to participate. What some are either refusing to acknowledge (or otherwise not grasping) is that SMN is being FORCED into being more or less a one-trick pony in this event. At least other jobs have reasonable means to still get decent rewards....SMN is not being afforded that luxury. Sure, it can try to go-balls-to-the-wall with it's staff and all...but it is at considerably more risk than other jobs when a mob decides to turn on them. The other mage jobs are simply natively designed for handling such situations much better than SMN--it's not just a difference of gear options, some have native traits/abilities/spells that afford them more safety when things get ugly. Can you really blame them for taking advantage of the one thing they can really count on to get decent rewards in this event?
Consider this: how many undead were slaughtered unmercifully with the cure bug?
http://www.youtube.com/watch?v=6I-X7a7AONI
Now, THAT was broken, and was appropriately fixed.