Youre talking like youre assuming im maining a dps? In fact, I main WHM/AST through every kind of content and SCH for more casual content.
Also,if i DO happen to play DPS, you can be very sure I'm doing just fine with my dps.
As for your first question: You need to optimize how to use your healing skills in order to dps more and you need to know the fight very well to guesstimate
incoming damage etc. So yes, it does make you a better healer because it takes FORESIGHT.
Also,if you had read at least half of this thread, youd see that removing cleric stance would make more healers quit than keeping it the way it is.