I did it back in November and have been advertising people to do it since, but if you're a High Elf supporter and you haven't unsubbed yet, it's about time.
If you remember, during Blizzcon last year, Alex and Patrick had a separate interview and said to stay passionate about High Elves and the discussion for them.
This is no longer Blizzard's outlook on the situation.
On the official forums, threads about High Elves are being locked, including the megathread. A GM response said that the problem reached Blizzard long ago, development is aware of it, and development addressed the issue in multiple Q&As. They don't want people providing feedback about High Elves anymore.
There is absolutely no reason a High Elf supporter should be giving Blizzard money at this point. It's clear that, if they care about feedback at all, it's the public eye variety -- and even then, they probably don't care about it much. The best place to provide feedback to Blizzard, even about High Elves, is primarily their Twitter and arguably their subreddit, though to a lesser extent since they have control of the moderation there. Tertiary discussion sites like MMO-C are probably still okay places to discuss, but I'd be willing to bet it's more akin to containment than an actual place for feedback, similar to the discords.
You can keep up the discussion if you want by hitting twitter, but other than that, I'd drop all other forms of feedback and I'd especially drop your sub. Money speaks more than anything and Blizzard's not putting out any fires till November. Unsub and stay unsubbed if Blizzcon doesn't provide what you want from the game. Sitting on the game complaining about High Elves and sitting in a containment site like MMO-C isn't doing you any favors, it's just shaving years off your life and wasting your time.