People change professions. Maiev was no longer a priestess of Elune when she became leader of the Watchers, Califax was a Keeper of the Grove, something the Elune Priesthood had no direct control over. Malfurion knew of her idea and knew it was a shit one, because Tyrande is an utterly terrible and horrid person.
But people like her because she's a hotheaded dumbass? Where at every turn she makes bad mistakes and Malfurion needs to fix them because of her ignorance and stupidty?
I think it's best summed up how much of an utterly indefensible character Tyrande is when they are tasked with destroying the World Tree. Tyrande says that they might lose their immortality, and Malfurion, being the only voice of reason within the Entire Night Elf Society since the dawn of it says the best line in Warcraft 3.
"If pride gives us pause, my love, then perhaps we have lived long enough already."
People always harp that they want a strong Night Elf Character, yet they go for Tyrande every time. When Malfurion Stormrage is the perfect example of how a Night Elf Character should be.
Stoic, Wise, Primal and Noble.