What I like about sceptics is that in good science you need critics that make you think: 'Crumbs have I made a mistake here?' If you don't have that continuously you really are up the creek. The good sceptics have done a good service but some of the mad ones I think have not done anyone any favours.
Nobody climbs mountains for scientific reasons. Science is used to raise money for the expeditions but you really climb for the hell of it.
The negative cost of Lewis and Clark entering the Garden of Eden is that later expeditions regardless of what they were intended to do later expeditions did not deal with the native peoples with the intelligence with the almost kindly resolve that Lewis and Clark did.