There is no question about it. Of course a boxer is expected to entertain. Entertain in the way of fighting though at the very least.
If they can fight and talk then that's even better.

If you look the guys you have named are all Americans. So they don't have to "Entertain in the ring".

It's entertaining enough for the Americans to see an American in the ring. That's what keeps the game ticking over.

Americans will pay money to watch an American in a ring even if his style is totally crap.

Can't wait to see Hopkins get his teeth knocked out by Calzaghe. Now Calzaghe with his combanations and fast punches is something good to watch.
How Hopkins is still above him in the pound for pound stakes is simple. He is American and it keeps Americans interested.
Just my 2 cents.