if you insist on talk mods.....
For a example, I can write 2 lines of code and I don't have corruption in Civ IV... for doing that in civ III... well, you can ask to the corruption patch mod maker how many time and effort he spent on that
Oy stop me from all this reposting...
OK yes LIke I said the corruption patch can be made easy way I just gave the 'better' way for overall gameplay. That was of course by adding improvements and wonders and even the vassel patch. Your right Thats a lot of work, also why you get those 3rd xpak mods I mentioned cuz they don't deviate from the core game we all love ; )
Civ'3 overtime made about 4 in 1000 float up. In civ4 you got some mods like these but again,there handicapped by hardcoded flaws which make deep constraints to freedom of size, hindering performance by mid to late late game.
Further more in this regard ..and already previosly stated,

(sigh!) Huge maps are something you
need to properly drive up the '3rd xpak' expanded tech tree.
These types of "patches cure "plain" game ailments by way of newly added "improvements' and 'wonders'' and even resources! Techs are needed and money is need to get the techs. You see the problem? You need a lot of tiles for a lot of civs to make the game fun and as challenging as it should be
Whew, that shoulda bin a copy n paste job to. See why I rush my typin?
OK and the 'fast way': Its much easier, any jerk can go into the Editer's city limit and turn the 'optimal city #' dial up to 999 citys or whatever.
Part duex would be hit the Government menu and turn all the Gov's in the game to Corruption status: "communal"
Whole job takes no typing and few clicks. You might get about 2 red sheilds per 'pop 20' city . Its not a very real patch. You just cut the problem thing out like a tumor leaving a wide gap in gameplay. Kinda like if you deleted civ4's unreal maintence and left a hole where challenge should be
Civ3 replaces with a new challnge: balance between maintence and corruption but see, I got into this already.
ITs Things that add to the game or save gameplay that consist as a real 'corruption
patch' Also why the performance and easy moddin are so imporatant as a whole like I mentined over n over.
Even the tought stuff like you say, its there for you to download and
(BIG THING) add new patches to right away!. Much easier then civ4.
Example ALright take " Balancer Reloaded" Its got the better then "pro grade" Pollution patch and the corruption patch I talked about.
It dosn't have the army patch on its " plain" version however .. Easy enough. Go to the "army" in 'units tab' to increase the 'health bar bonus' to whatever it says then " Game setting tab' to adjust the 'units per army' to 1 .
You just repeat from where you saw the idea of better implimentation onto the Balancer Reloaded editer and save.
No crash due to incompatible lines of code which can come up sometime way down the line to ruin your game. Ya, thats a real facet with amatuers modding in civ4 that effects real people unfortunatly