The Observatory would be nice as a "planet discoverer," BUT a picture function would be good as well, allowing you to get more science just by taking pictures. For example, if you discover a planet using the camera, you get 1.5 times the science than if you just found it just by looking. The farther the body is from Kerbin, the more science you get. Science points also allow you to upgrade the telescope in the Observatory (although they're ridiculously expensive) and database (same price), allowing for more clear pictures that can be stored before having to send them to the R&D Center, and thus more science. Also, special astronomical events, like the two kinds of eclipses, and transits. They would give you bonus science.