The only ones in favor of layering are probably the ones, that never experienced a “no layer” Server from the start.
Example: You can´t even compare the current classic wow realms to a private server in terms of community.
I play on Firemaw and before that i played on Lightbringer. It was night and day in terms of the social aspect.
There is no such thing as a community on classic wow. Layering made sure of that.
Reenabling layering will only give the scum exploiters yet another way to make gold.