The idea of using it to balance the AI, particularly on the naval side, is intriguing. While El Justo has done a fantastic job with ensuring that the AI make somewhat realistic build choices, there seems to be a point in each game were the AI abandons building his navy. Auto producing some of these units would force the player to continue to face an AI naval threat which I think would be a good thing.
After it's built 9,001 Battleships and they all sit in Gibraltar? Auto-produced Battleships would be nice, as that way you wouldn't get so many of them stuck doing Convoy duty ... (Seriously, France. We know you like to protect your ships during the 3-turn run from Tunis to Marseille. You don't need 30 obsolete BBs and 10 modern Battleships to do it!).
That said, auto-producing ships-fleets even (from more than one building obviously), armies, planes, artillery could actually make the game hugely more interesting and competitive- for the AI.
If such buildings weren't capable of being built by the human player, the playing field could leveled a bit in late games. That is if the AI still utilizes the units, which would have to be tested, and surely as it's now August the next version is soon to be out
One problem with this is when to allow these buildings to start being built. At the beginning the player would be contained, but if they are allowed to build them then it takes away the trouble of finding a unit building: improvement building balance and would by the middle of the game probably have the player dominating. It's an intriguing thought though, as these could be rather easily worked into the game, it's just a matter of how to use them to the best degree.
Perhaps a Small Wonder that does the Auto-production? That way the human can't spam the buildings, civs that are landlocked can build them later, civs can't capture multiple buildings to auto-produce more than one ship/whatever at a time, and the construction location can be moved if desired. For example, something for Battleships might be ...
No BBs can be built, at all.
With the first BB tech of the Age, a Small Wonder is available that Auto-produces the *first* BB available in that Age. As the civ gets BB advances, the BBs can be upgraded, but the SW only produces the basic BB.
With the second BB tech of the Age, the SW from the *previous* Age is obsoleted, so for a time, a civ can have two SWs auto-producing ships, although one will still be producing obsolete ships.
Only the Auto-Produced BBs can upgrade, but the cost for Upgrading is 0 - this is to (hopefully) induce the AI to upgrade its basic vessels (as it will upgrade the King BB units if it gets the chance) and to prevent the Human from upgrading all its BBs continuously, forcing them to decide how obsolete they want their BB fleet.
I'm not sure how workable that actually is (it seems simple enough to me, albeit long and boring to get done), but something like that ought to work.
Not that I expect anything to be made of it officially.
I've actually found that if you give all arty(except mountain guns for balance reasons) blitz the AI will actually build and use arty.
It's been brought up before, tested, and rejected by El Justo.
I my games all the big boys build about 70 field guns and about 10-20 howitzers by the start to the middle of the second era(except the germans who, like the human player, realize that their howitzers are much better than their field guns for not much more) they also use them offensively, albeit in limited fashion, but seeing an AI stack of doom supported by 2-4 guns is pretty neat,especially in the colonial theater, where everyone is pretty much equal a few guns make a big difference.
Stack of Doom with only 4 guns? And I haven't found "a few guns" to make much of a difference at all, unless you're Germany and get excellent Howitzers to blow up everything. Ten is the minimum I've found to achive anything like a reasonable difference in time to conquer, as anything less than that and you fail to consistently ping enough defenders to prevent most of them from healing enough damage to make a difference, especially if you're stuck with piddling 1-RoF guns.
The problem with getting the AI to use guns seems to be that it is programmed to first use it defensively and only once it's defensive needs are met will it use them offensively. But the computer views arty as next to useless with its 0 att and def values, but absolutely loves anything with blitz.
Strangely, I've seen France, Germany, and the Boers build and use artillery offensively in Africa, although not terribly well. They'll send a stack of 3-4 units along with an Artillery Unit and randomly ping units or cities. I did once see the Boers park a Howitzer and two Field Guns outside a German city and consistently Bombard the city, though. (This on Lieutenant Difficulty, IIRC)