What else is there?? All you can do is either grab from behind and interrogate them, slit their throat or make them talk. There's nothing else you can do.
As far as contextual melee, you're looking at it like the game will do an action when it says to do it. That's not how it works. Say you're running towards an enemy and you hit square, in that situation drake may dropkick the enemy. Run while blind firing and then hit square and he'll clothesline the enemy. If you're coming down a flight of stairs and an enemy is below you and you hit square, he'll football punt the enemy. You have a shot gun in your hand, well the melee attacks will use the shot gun to hit him. It's not bad at all. I think MGSV has some light contextual melee like if the enemy has a gun in their hand, Snake will disarm them and stun them with a knockout punch. It's pretty much the same thing. Obtuse and unwieldy is not how I'd describe UC4's melee.