That is a little difficult for some to do when feature roadmaps don’t exist 
Couple that with Blizzard’s unwillingness to announce that something is time-limited until close to the end, and you have a combination that drives animosity.
I wonder what the effects would be if Blizzard plainly stated “here’s this new feature, you have until the end of the expansion to do it” rather than them waiting until the final patch of an expansion to say “oh by the way have fun this is going away soon!”