My goals are very similar to my original ideals (see my essay): a piece of software that easily lets you build nice maps that can be rendered various ways, zoomed into and out of, and can be edited with geological phenomenon (an asteroid dropped here, plate tectonics here, mountains raised here, etc).
It should keep topological information, as well as more ordinary 2D map information (roads, cities, etc), since topological information is very interesting for roleplaying people.
It should produce attractive maps in a variety of styles, and should be able to print distorted maps (results of poor cartography).
It should have a snappy UI that lets you edit maps really easily.
It should be easily extensible and programmable, with new editing tools being a breeze to add.
It should be easy to write.