Discussions: what one rule would you like to add/change to 40K?

So, I was thinking, there are many different game systems but a lot of my reader base are 40K fanatics. The 40K rules are great in my opinion but I have seen some really nice ideas from other game systems.

My question to you is, what one rule would you like to add or change to 40K. I would like to see squad coherency changed to radio coherency. What I mean is that instead of models having to stay within 2" of each other everybody has to stay within say 8" of the sergeant and if he dies you just nominate another model to become sergeant. This encourages the idea of all the men piling in and not spreading out along the entire board.

So, what would you change. Thanks for reading,

Jacob.