It really goes against the fundamental point of trust levels to elevate the level of access a user has without informing them in some way, doesn’t it?
They’re there as much for the users as they are the site operators. How would anyone know they can now send a PM if they aren’t told? At TL1 users are also prompted to complete their profiles, something they may not want to do at the point of registration. I find that profile data to be pretty helpful when responding to people. A site setting would dead-end these things.
If people are fussing about two messages which let them know they have a greater degree of access and freedom, then they’re leading pretty charmed lives.