Personally I don't have any issues with the treasure hunt and I don't see why anyone should have.
The coins/supplies rewards are very little for anyone whom aged up beyond the middle ages and the fp's are also extremely rare, or atleast for me they are. BP's are always great ofcourse but you get plenty of em from aiding so I don't see the issue.
With that said I agree that having an toggle or option to exclude or include this in our game would be a welcome idea. More options is always desirable rather then (minor) game mechanics been forced on you.
Another option would be to, instead of removing it, to change it into something better:
I'd prefer if they changed the "minutes" into "days".
Also, you should have to invest supplies and gold for the expedition and then you wait a day, etc to see what you find/win.
Maybe you can also invest military units just in case the expedition comes into trouble. Maybe investing units (which you don't get back) increases the chances of success of the expedition?
I think you are on the right track with this idea.
The game is all about managing time schedules in pairs of 4hrs/8hrs so it makes little sense we have these "expeditions" for short periods of time. As if we'd be playing this game all day long and if that would be beneficial besides the expeditions themselves. In some rare cases it might, such as for big GvG players maybe, but for the common player it would be more convenient to have larger gaps between the expeditions themselves. Last I agree with sending a military convoy of some sorts perhaps to improve chances for better rewards?