Why avoid popular races that have been asked for over a decade?

I know there hasn’t been much talk about Forest Trolls in this thread, but as a race concept, they are a popularly desired one. Now, I know, there’s a high tendency to write them off because they weren’t announced at Gamescom this year, and admittedly, this feeling is deserved. Blizzard has one of, if not the most, abysmal track records of all time when it comes to fulfilling popular player desires. However, I think there’s still a chance that we could see Forest Trolls become a new race. The reason, as I see it, is because they are a race that requires nuance, which is to say, the reason they weren’t announced is because (1) they are a race with an incredibly complicated history that needs to be further developed in-game, and (2) Blizzard is likely withholding the announcement so that it can be a surprise during the expansion. The second of these reasons is one that I find quite stupid, as all it does is cause people who want forest trolls as a race to lose hope. Blizzard, however, seems to think differently. But I would encourage people not to lose hope. The backlash over forest trolls not being announced at Gamescom was immense (for a few days, admittedly), and it’s unlikely that Blizzard didn’t catch wind of that. Popular streamers and YouTubers have also talked about the race not being announced and have expressed their disappointment, which is another thing I imagine Blizzard will take note of.