It would be nice if a command could be performed as a player/someone with permission went through a portal. For example I own a Paintball server and when a player is in the paintball lobby waiting for a game they can't PVP as it's part of the plugin. But there is a PVP Arena also which isn't managed by a plugin, when they enter a portal to go into the PVP Arena and try to PVP they can't as they're waiting for a game to start.
The command would be "/pb leave" so the player would leave.

Thank you for reading this.

Binding commands to portals is already possible, just use the handlerscript portal property.