Donīt think that all those scholasticism is hindering the mod development to such an extent you might think of. Just look on the other Roman mod for Medieval2:TW "De Bello Mundi".
There you have no large essays about all the factions and it looks like they will have more simple gameplay-mechanics. But still they are working since atleast 2008 and are also not finished yet:
http://www.twcenter.net/forums/showthread.php?t=143858
I donīt know anything about modding but I guess porting a game to another timeframe is the main reason why it take so long to get things done. Most finished and polished mods for both RTW and M2:TW are dealing with the exact same timeframe as the vanilla game. Doing any other timeframe results in much more work I think.
E.g. you can not adjust simply the vanilla units, traits and ancillaries and so on. You have to create most things completely new. Different buildings (various temples instead of only churches and mosques), using the religious system for other things, making new agent models, portraits and donīt know how many other things.
Then there are other units and tactics on the battlefield. You probably have to create a new AI to deal with the new units and balance things out. Might also be a huge task compared to a Medieval mod where you "only" need to adjust some setting values here and there.