I would love to start modding Civ5, but it seems like a whole lot of things about it are difficult to impossible to change due to hard-coding (new city/building graphics, new resources, sounds, terrain/feature graphics, etc, etc.)
The type of mods that are really interesting to make or play are total conversion mods like FfH, Dune Wars, or Planetfall (or Firaxis' own Final Frontier & the modmods thereof) that actually make it into a new, different game. The Modbuddy setup seems designed for a profusion of incremental "mods" that do things like tweak the strength of Swordsmen or add some techs to the standard techtree. I'd much rather just remove *all* the vanilla content and start adding new resources/terrain/units from the ground up, but if there's hard-coding of stuff you can't access with XML it seems like this might not be possible.
I will say that some of the initial attempts at fanmade modding utilities look like incredibly promising strategies that could make Civ5 modding a lot more achievable if they could be made to work:
http://forums.civfanatics.com/showthread.php?t=395209
http://forums.civfanatics.com/showthread.php?t=393390
Unfortunately when I tried to install & use these neither seemed to be working with the current game (or maybe I'm just going about it wrong..) Something as simple as an Excel spreadsheet allowing you to enter unit stats in table form and format them into XML would save *huge* amounts of effort and errors for modders, and is way more helpful than the modbuddy approach of using SQL queries that let you do odd things like add 1 strength to all melee units. Does anyone know of any useful mod tools that are currently useable or in development?