"...The same old fears..."
"...wish you were here..."
Sorry 'bout that, couldn't resist quoting Pink Floyd.
Aside from establishing that fresh, potable water once was present on mars, making it "habitable" at one point in its early history, the observation of stream deposits was especially exciting for this geologist. That textural observation could not have been made any other way than direct observation.
Plus, it has been a proving ground for technology that we will hopefully use to continue to explore our solar system without the huge expense of actually sending humans there.