M.U.L.E. at least had an NES port.
And, as far as the quality of OT - I think that it's well made.
Well ENOUGH anyway. If needed they could expand the graphics, gameplay and strategy elements to suit a broader audience / create more entertaining gameplay.
Oregon Trail's gameplay style reminds me a lot of the simplicity and form/factor of one of my other favorite basic-in-design/endlessly entertaining action/strategy games "Defender of the Crown" (which has had two excellent versions in recent years - for GBA and PS2).