It kills sense of community, since it is the only place where you have pvp interactions after bgs release. And community is what made vanilla great.
I do not mind having x-realm AV, there are always many new faces, but it ruins WSG(and AB later) especially premadeVSpremade games, when it is actually important to know your opponents.
And of course current iteration of Alterac sucks, but it was said many times.
To be honest with 4-6 realms of 2-3,000 players in a battle group in Vanilla you’d probably have a better chance of recognizing your regular opponents than on a single server with a pool of 15,000 players to match with nowadays.
The anonymity between playing in a pool of 15,000 and 150,000 players makes little difference.
My team certainly had no trouble getting a good enough reputation in our battle group that the majority of Horde teams would AFK dodge us during patch 1.12.
Not like this it wasn’t. There was crossrealm battlegroups, where servers were matched with 4 or 5 others and not connected to the rest of the servers. This meant you regularly played with people you knew / saw on your server, and also you met and became friends / opponents with people on other servers.
And you also got the benefit of faster queues as server was not alone.
Now I haven’t yet had the chance to play wow since the patch went live, so I can’t really judge the current system. However if it just matches you with people on any server, that is not remotely like the system in 1.12