My 2 cents is that if we had game systems in place that allowed and expanded businesses, cycled items out of the economy via coded systems (for instance), other than basically just RP then yes, more than one would be acceptable. But in reality they would only be used for hauling craft items for a fairly small community (things considered).
Don't get me wrong, I hear and understand what you are thinking, but we just don't have enough coded "business systems" in place to encourage and in fact remove said 'items' or the influx of gold and crafting results/raw materials this would cause to flood the market. In a perfect world, or the medieval world, then yes, I would agree...right now though, it would not be a good idea for the player base as a whole.