You see. Many players have already made their choice between Shazzrah and Golemmag. They weren’t expecting new realms to come. They already got involved in the community, and aren’t willing to change their mind.
As of now, both Golemmag and Shazzrah are full of the more-hardcore players who prepare in advance. And Gehennas is a low population realm. But we know that there will be a burst of new subscriptions around launch day. And, those players should see the old good “Suggest Realm” screen, which would point them to Gehennas, if they choose PvP.
We know that there will be more casual players coming to Classic. Those, who don’t care about name reservation, and don’t want to waste 2 weeks of sub. And also, there will be new WoW players - the main reason, Classic is cheaper than BfA.
Therefore, in my opinion, Blizzard should bring back the “Suggest Realm” screen.