Agreed. In 1e you were worried about carrying huge quantities of coins, coppers, silver, electrum, etc. Also most PCs collected the arms and weapons of their fallen foes. In 4e, the amount of coins are less with the parcel system, and the equipment of the fallen is often ignored or considered of little value.
Also in 1e the use of miniatures was much less common, so foes could be defeated without worrying where the party's mule was located and the mule wasn't targeted by monsters unless the DM was ticked at you. In 4e, would you have to place the mule on the map and would it be slaughter by Aoe attacks, etc? Makes it less useful in 4e.
If someone wants a mule, charge 20 gp, and don't give it combat stats.