Tile editor ideas:
1: Assymetrical XYZ scaling as already stated above
2: BUGFIXES BUGFIXES BUGFIXES
3: HSV color picker (not only to tile editor, all things color-related in the game, faction editor included
4: A tool for making circular arrays (rings) and such while in tile editor, currently hand-rotating objects to place them is a pain in the ass.
5: Possibility of offseting object pivots so they can rotate around other objects and not around themselves when animated/transformed (would require new XML data though)
General stuff I found currently:
Abolish all integrer values for game variables where nonwhole numbers might apply, such as mana regen, resource production, prestige, etc (most of them are floating point, but some remain such as A_Manaregen), careful balancing often requires nonwhole numbers.
Allow us to properly define how often/clustered resources spawn (perhaps add python support so we can code rulesets for resource spawnage?), currently this is another touchy issue where often you either get tons of resources or none at all. Rarity and other controller constants seem to not work very well at all, or their behavour is chaotic and some documentation would help a lot.
A visual interface for defining tilesets of analogous buildings within kingdoms/empires and proper code implementation of such would be interesting too, currently for a tileset one needs to define a whole new building from scratch.
Add the possibility of "tile families", sets of similar tile designs bound to an improvement/building/prop/resource/whatever which get picked randomly when placed in-game for adding more variety so huts don't look identical up to the farmer in the garden for instance.
Perhaps implement all those local/rummaged resource stuff which got commented out and simplified in favor of global economy so we can make our own mods with local/trading economies?