From a RP perspective that would be great. Would love to cart the wife around with me while I go mine some ore.
I would love just the cosmetics of it, but if it came with benefits of some sort, fantastic.
Over encumbered passenger can ride with you at normal speed. A simple, but appreciated benefit. One man drives, a passenger (or two or three) run about harvesting until everyone is ready for the trip home.
Many benefits could be incorporated into “mounts” without even considering a speed buff.
Rolling re-spawn point. It could be an additional save point, like a bed or fiber roll. Just so you don’t have to keep picking up a roll and or placing a new one as you travel around in dangerous territory.
Siege wagon. Could block some archer fire while you work your way through the walls of an enemies base, or have a miniature catapult/ballista on it. Think of a battering ram, back it up to an enemy base and thump on the gate a little.
Trade wagon. Load it up with goods, allow for the trade of X for X. You set the prices. Wood for Stone. (X) for Gold Coins. You travel from base to base trading away your resources. All through a window interface of the wagon. No more dropping bags or being “scammed”.
Gypsy/Dancer wagon. Just a fancy canival type mash up of trinkets and incense and music. Complete with a thrall slot (or two) for a complete experience. Provides user with mobile, durable buff for entertainment/healing purposes.
Fun to think of the possibilities, even if the chances are remote, could always inspire a dev to get creative in that direction.
Here’s to hoping!