I believe I read somewhere by Blizz that mastery is not supposed to buff ALL your damage, you're probably right.
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If they are to keep Empowerments gains from SS, would a model where SS costs much lower AsP and it buffs either SW or LS (but not both) giving them different effects according to their "situational purpose" work? Lower SS cost would make the rotation feel faster, different empoweremnts would give you a better choice on how to spend it and not become "cumbersome" to save it and at the same time make you worry too much about capping.
Also how about casting Starfall kinda marking the mobs inside of it so the next MF/SnF will get buffed for their full duration regardless of the Starfall uptime? It still allows for skilled players to pool AsP for the right moments to aoe effectively, since the longer you have to build AsP the longer the mobs have unbuffed dots on them, but if you were prepared you get the full starfall empowering dots benefit from the start.
And if these suggestions are mathed out to be viable/more fun/improvement of the current iteration, are they too mechanically different that we would never get them at this point? (Still trying to understand what's supposed to be the case)