I’ve posted a guide in several megathreads of how to send in-game feedback supporting races you want playable and referring to their respective megathreads on here. I figured I’d share it here also:
Once a month on only one character, I send an in-game suggestion for the races I want playable. I do one suggestion for each race and refer to their megathreads on the official US WoW forums for more information. It’s something I don’t regularly do, as I don’t want to spam the system, but it is something I try to at least do occasionally.
If you’re interested in submitting in-game feedback for any races you are interested in becoming playable, here is how to get to it in game:
Step 1: Press ESC to bring up the general menu.
Step 2: Click “Support.” It’s at the very top of the menu.
A new window in-game should load. It can take a few seconds for it to load completely. Underneath the “Search World of Warcraft Support” search bar, you should see a line of square images that refer to specific categories of support.
Step 3: Click the “Submit feedback or bug report” square. It should be on the far left when you first load the support window.
It’ll take a second to load that part.
Step 4: Click the lightbulb icon on the right that says “Submit a suggestion”
Step 5: Click in the text box on this window to begin typing a suggestion.
You’re now ready to submit an in-game suggestion!
It’s limited to 500 characters you can type, so you have to be a bit creative in the limited space. As I said before, I usually do one suggestion for each race I want playable, giving a very brief mention of the race, the faction I want it for, and why I feel they’d be great to add. I then make sure to type the name of the associated megathread, assuming they have a megathread, and mention they’re on the official US WoW forums, stating to go there for more info, such as ideas, fan support/designs, ongoing discussions, etc.
When you submit the feedback, it states you won’t get a response, but that it’ll be looked at in some way. Now, this wouldn’t be a sure-fire way to get a race playable, but it can’t hurt to do so in my opinion. After all, we have to show support somehow!
So for those interested in supporting a race you want playable, this is how to do it in-game. As I said, I usually do this once a month (on just one character) at most so as to not spam the system. However, multiple people doing it could help a lot to showing support for races we’d love to see playable.
Also make sure you’re submitting a suggestion and not a bug. I mean, yes, the character creation screen lacking playable Furbolgs is quite the game-breaking bug (with an easy fix!), but a suggestion will likely be received better as opposed to sending that as a bug report.
I’ve gone ahead and did this for Furbolgs in-game this month and will continue to do so with my monthly in-game feedback sessions. You never know if it’ll help!
Playable Alliance Furbolgs is a bear necessity! 
