“I want to play with my friends” is an argument that WOW TBC Classic Gold is not very convincing to not have balanced servers or Bg pools. Furthermore the possibility of changing factions, would mean they could be able to play with their friends in alliance instead of horde.
Transfers between servers are always a mixed bag. You never know if your targeted realm is as good as the one you have previously and even if there’s no queue it could be a shambles, if not dead realm. I’ve experienced this firsthand in Vanilla which was where my guild transferred to a new server, and after a couple of months, the population dwindled to a few hundreds at the peak times.
While it’s the case that nobody has been capable of swapping characters with their characters however, they could have when they felt that the queues were too long.
The same argument for server transfers also holds true in the case of switching sides. It is impossible to know whether the population is viable for long-term raiding, or any other type of content. There might be shorter queue times , but you can’t even be able to fill a random kara attack within a couple of months. Even if it’s the same server, each side is completely different in growth and player mentality. Side transfers can solve the issue of waiting time and other issues.
The idea “I would like to play with my buddies” is very valid. But the problem isn’t with number of servers as it typically impacts open-world pvp, but the composition of the battlegrounds and the incentive to buy Burning Crusade Classic Gold join these battlegrounds. This is particularly problematic since each region is balanced overall as well as within a battlegroup of their own region, but is experiencing queue times that are 4-5 times longer than the entire alliance.