Invisibility STILL gives you a jump on a fight. Someone can be sitting completely still and waiting on somebody to walk by, then boom, they get a head start on the fight. Not only that, but the person they jump is confused because of the jammed radar. Plus, that jammed radar works your OWN teammates as well.
Armor Lock definitely lasts more that 3 seconds. While you're waiting on the person to get out of it, their teammates can come up and kill you. The point I'm making is that if you're in the middle of a firefight, and someone goes into AL, it completely ruins the flow and balance of the game.
Anybody who claims that AAs don't ruin the game and say that Invisibility and Armor Lock are fine are obviously not true Halo fans.