And Garrosh fans were pissed because that was his end - it was not enough for them. They wanted that character further milked.
For all the complaints about Sylvanas hogging the screen from people who hated her to begin with, she had fans who were over the moon with her arc, and are eagerly awaiting news about her exploits in the Maw.
It is almost like people enjoy different things.
Clearly, there are Warcraft fans who enjoy the Scarlet’s role as villains, and want to see their story presence return and expanded. You simply saying : "I hate when faith in religion is used in a negative light " does not mean every one else shares your view.
Many fans are looking forward to either Yrel and her Lightbound or the Scarlets making a play - because they have been teased. And Turalyon has spoken about reclaiming lost Alliance territory, so people are waiting to see what that will look like. The Light has been slowly set up over multiple expansions as more than just some vague power people revere and draw energy from. Some of us are waiting for the pay off, instead of more loose threads that go no where.
It is a matter of taste. I would not say quantity is the major factor - quality is.
Something can be used often, and it can maintain its entertainment value through quality. The Old Gods are used as villains much more than the Scarlets, and people still clamor for Old God lore. Probably because it lifted heavily from Lovecraft’s cosmic horror. If people complained about Nzoth in BfA, it was that he was given short shrift, and he deserved more. Not that they are over used.
That seems ludicrous. You want Blizzard to develop an enemy out of no where, to fulfill the same purpose and do the same actions as the Scarlets - but with a different motivation? Just because you do not like faith in religion being maligned? That is part of the problem with Warcraft lore - Blizzard rushes to develop new stuff while leaving perfectly good older stuff in limbo.
The survivors of Lordaeron who want to chase out the Undead and reclaim the land for the living has been part of the Forsaken identity since its inception. It is already part of the narrative.
It is only quite recently where the Alliance started considering respecting any Forsaken claims for Lordaeron, and mostly through Anduin’s commands and Faol’s presence. That may not stick.
Having survivors of Lordaeron attempting to reclaim their land from the current denizens does not cheapen their narrative, if that has been their narrative for a long time.