The reasons that there are so few mods is that it's very easy to invisage a nice story for one, and yet, very hard to actually execute it through the constraints of the engine, both visually and mechanically.
Even something as simple as seperating out 'glow.bmp's uses as different files would be helpful.
FYI, all mods save exactly the same way Darwinia does, you can save progress overall and progress in a level, you just need a profile for that mod. Is the method that Darwinia uses to save progress in a level perfect? No, since Stricken still obviously has the problem that your squad unit isn't in your task bar most of the time so it doesn't get saved. However, if in an update you change your mod's game.txt file one iota, your user needs a new profile.
Wait a minute... I need to investigate something. It's RE how does a saved mission level in your profile know which engineers etc to put in your task bar.
Anyway, maybe I should like, make a list of dos and don't, or at least trivia - how many people know having an instant unit officer with a state of -1 (which is what they get when you instant unit them) will make Darwinia crash when you exit, seriously? (yes, it is in the bugs forum, though the picture is probably gone now)
Finally, yes, I could make more mods - I simply don't have the possible stories to go with them, ie, the thing that makes you actually have any interest in making a mod in the first place. In fact, fixing up Hacked made me want to restart Droughtwinia, the idea was basically a mod technology demo, showing off what can be accomplished (except new models, I hate doing those, keke) - so, watch this space. Or possibly a different thread.