Penalty and red card.

After debate last night, we all know the rule is that a last man challenge in the box, which denies a clear goal scoring opportunity is a red card offence but is this too harsh?
To play devil's advocate a bit, would a yellow and a penalty not be sufficient punishment or denying a clear goal scoring opportunity?
To play devil's advocate a bit, would a yellow and a penalty not be sufficient punishment or denying a clear goal scoring opportunity?