The problem is that there is no good way of replenishing the film supply in space. Shuttle missions are costly to say the least, and we haven't always had the Shuttle. A photo satellite's useful life was determined largely by the film supply it could carry.

The other interesting aspect was retrieving film canisters. Basically, they were ejected by the satellite and an airplane literally caught them during descent. I'm sure some of those flights had their "moments". Not a 100% reliable method (nor cheap) but it was used for a good share of years.