Hardline is the way it is because DICE is off updating the engine for current-gen only, and they're probably not done with those changes yet. Hardline still had to support the older consoles, so any changes DICE was working on would affect Visceral's workflow too much to include.
Worth a shot. We never really knew what to make of it. It was so useful it became an integral part of mastering the Engineer class. When we discovered the charge meter on the PSP version we were all amazed.
When I say we I am referring the PlayStation 2 online community for the game.