Dissent is worthy of a yellow card and we shouldn't really need a naughty step with adults. How many times should a player be sin binned before he gets a yellow?
I am not strictly against it, I just think is a massive introduction unlike the ones you mentioned at the top of your post.
I can't see sin bins being introduced, it has to be a world wide introduction, it would change the game dramatically and make it even harder for the refs. I can see the players surrounding the ref, shouting "if it's not a card ref, it has to be the sin bin"
Could see cards being given out...
I tend to agree, unless it's a dangerous tackle in the box, a penalty and yellow card seems to cover it.
Fouling outside the box and denying a goal scoring opportunity is worth a sending off.