While I'd like to see the DLL released, it's actually interesting to see how much people can do without it. Later tonight, gods willing, I'll be posting v0.01 of my Mythology mod over in my Project forum. I'm continually surprised by how much we can do through the existing Lua functionality; it's one thing to add hundreds of buildings, units, etc. to the game, but you can use Lua to add all sorts of strange unit abilities: a Hydra or a Scyllae will grow heads (gain a free promotion) when they kill enemies; Rakshasas gain promotions from whatever units they fight; Valkyries heal the units around them whenever they attack, but the more units that get healed the weaker their attack is; when a Zombie kills another unit, there's a chance of the killed unit becoming a Zombie themselves (and Vampires get that ability as well, but the chance of spawning depends on the relative strengths, so Zombies have a higher chance); Dryads and Treants can plant forests and jungles. Or Building effects: temples to a god of Balance will raise Food, Production, Gold and Research depending on demand; whichever is lowest gets the largest boost, whichever is highest gets the least. Higher-level temples to a god of Healing will heal friendly units near your cities, temples to a god of Darkness will reduce the visibility and range of enemy units near your cities, temples to a god of Travel will make your units move faster when within your territory, and temples to a god of Storms damage enemy units near your cities (or near Tiamat, the high-level one-of-a-kind unit available to Storm gods).
Okay, fine, this was an advertisement for my soon-to-be-released mod, as I'll need some folks to test its balance and give feedback; the Project forums don't get as much random traffic as the main Modpacks area, and these forums in general are getting a lot less traffic than they used to. But it's still a pretty good example of how much we can do without the DLL, hence my bringing it up.
Yeah, that's the part that I think people are being unrealistic about. They hear "anything's possible with the DLL", then they're handed this massive block of C++ source code. How many months do you think it'll take before even the hardcore modders have any idea where to START making the changes they want? If Civilization was a small enough program for outsiders to easily dive into, we wouldn't be here.
The way I see it, at first a few good programmers will go into it and figure out where certain obvious stubs can be placed, and will be able to create a community library mod that adds all the stubs they've figured out into a simple XML format anyone can use. That is, you see a Building table that gives boosts for the presence of certain local resources, and you think "hey, we should add a table that lets Buildings give boosts for the presence of certain local Improvements as well!". Or they'll spot the little bit of logic that keeps buildings from recognizing negative Happiness values, and remove that limit. Or they'll figure out a way to raise the current limit on number of Promotions. Simple things like that, which the rest of the community can use to improve our own mods without actually delving into the DLL ourselves. (Sort of like how the Building Resources and Custom Notification mods allowed us modders to do things with our own content mods that weren't possible in the original XML.)
Then, in six months or so you'll start to see the first real "rule change" mods, ones that significantly change how the engine works (like FfH). I'm planning out a DLL-using mod overhauling diplomacy and espionage, for instance, but I'm not expecting it to be functionally complete for a long time.