Stock tires should not be considered as a decider between purchasing a bicycle IMO. They wear out with use and you can always find a better tire for your specific conditions.
While rim width on the MTB could limit some pure road tires, frame width on the DS could limit fat tires. Frankly either one could accomodate modern slicks or semislicks. The MTB is less limited than the DS when it comes to tire choice.
To be honest, the Rockhopper wouldnt be ideal for the riding portrayed in the pictures above either. Even on the XC course, the suspension would pack in, and the lack of rebound would make you wish you were on the rigid Klein in the above post.