They was expecting a thriving civilization with advanced medical technology.
Were they? The composition of the Prometheus' crew does not suggest this. Would you bring a geologist with you to meet an advanced alien civilization? Mercenaries with flamethrowers? Vickers clearly had no interest in making contact with anything.
I got no impression that the crew was really prepared for or expecting anything in particular. They certainly weren't trained for it, as the mission was only revealed to most of them when they got there.
It's like they threw the whole thing together at the last moment and placed classified ads for the lowest bidders. The most advanced FTL ship Earth has crewed by people they found on Craigslist.