and it still wouldn't be

Nevermind that someone can simply roll an opposite faction toon to whisper and berate the player that they couldn't insult from their main. When anyone can do that, what's the point of not being able to speak cross-faction? Especially if being PvP flagged would disable the cross communication to prevent the sides from revealing their playbooks/plans.

Making a toon just to insult someone (or relogging if you actually have a toon on the other side) takes time and effort. Once, in a very very early phase of WoW, there were no languages. Now, imagine how people roasted each other whenever there was a player kill in Hillsbrad foothills on a PVP server. That had to be stopped. Now all we got instead of that is /spit

For a long time you couldn't create opposite faction toons on the same server. All your toons on any given server had to be all Alliance or all Horde. If you wanted to grief/troll "the other side" you had to have two active accounts. I think it was after WotLK that this changed.

If any race should be a translator, it should be taurens, for their druids communicate with night elves for centuries.

velutina, that was only PVP servers.

I've heard stories of undead luring Alliance by talking to them and then ganking them. It just wasn't too great for balance.

Bur!