Tag is also a Simple Action, so you could Tag two targets in a single Initiative Pass. The penalty negation stacks with every other thing, Vision Mods, Adept Centering, whatever, and Tag also gives everyone targeting the Tagged Icon an option to Free Action Aim, that would stack with a Simple Action Aim.
It's a pretty solid option for Deckers, Riggers, Technomancers. Rigger, Simple Action Tag, Simple Action Order Drone(s) to Shoot Tagged targets. Decker/Technomancer Simple Action Calibration, Simple Action Tag the Boss.
It's a buff that the entire team can use, so the extra dice can add up.