I would be very interested in improving map editing capabilities. Eliminating the need for a compiler would be a huge plus. Another point of pain is filling in large areas with tiles of a certain terrain type, auto placing of tileset transition tiles, and auto placing ridge tiles.
The scripting part sounds like the biggest and most difficult change. We'd need to make changes to the file format, and associated loading code. We'd also need a way of interpreting and running the extra data at run time. A full scripting engine sounds complicated. There are many things that can be done at runtime, so there's quite a lot of functionality to implement. There's also security concerns, but I suppose no more so than passing around DLL files.
For auto tile placement, that's more of a meta data issue. We would need to add information about the tiles that allows them to be auto placed correctly. It's tedious, but it should be reasonably simple. At least it should be simple once you know how you need to classify the data.
Another meta data issue is classifying the tile groups. Some are like the doodads in Starcraft, meant to be pasted as a whole. For example, volcanoes. Some are collections of individual tiles, where a single tile from the group can be pasted, but you'd never want to paste the whole group. For example, a group of single tile meteor craters. Then there are some groups that can be pasted as a whole, or have individual tiles taken from them, such as groups of plain flat terrain. We should try to augment the existing group data with more meta data that allows for better automated processing.
