Yeah they do need to overhaul the targeting system. I made a little thread a long time ago about how I think the best way to fix it would be. I think it went ignored for the most part.
I use a controller so that will be my example, but the keys on the keyboard would work the same way.
Anyway it should have a 360 targeting system. To do this while you're unlocked you point the left thumb stick (or keys) in the direction of the person you want to target then lock on. This would make it so you can manually choose who you want to target, even people behind you. If you have an enemy behind another enemy then you keep it held it that direction and it would cycle between the two. If you don't care who you lock onto then just leave the thumb stick or keys in a neutral position and the targeting will work at it is now.