Like you said, there are other chase scenes in the film. It didn't need another action scene, it needed a scene of substance. The scene shows yet another piece in the make-up of who we know as Bond. He dragged Mathis along with him, inveriably got him killed, and will obviously feel guilt over it. But it also shows who Bond really is. He cares, the death scene is an incredibly intimate moment between two friends, not unlike battlefield experiences many soldiers have. When death is inevitable, everyone just wants to be held and reassured, no matter how tough or emotionless they may seem in life. I think it was shot perfectly. But it also shows Bond's coldness and dedication to the mission once Mathis is dead. He dumps the organic Mathis in the trash bin, takes the money he will need and moves on. Camille comments on this, afterall. The action scene within the scene where Bond takes the two men down is well done, and quite enough in my opinion.
"Never send a man where you can send a bullet..."