Please, please, please let us keep the mod packs! I am using Heed's resource tabs (those "little square blocks with blue and green letters") and I can't imagine playing without it.
Like others said, the advantage of using the mod is extremely small, and cheaters can much more easily just look into the spoiler threads or reload the game from the start. Also, it is impossible to check if a player has been using a graphics mod or not (unless he is stupid enough to post a screenshot when using that mod).
So, IMHO, a good compromise would be to compile a list of allowed mods, which would include pretty much all of them except the biggest ones (like Alimetando's newest), and perhaps add one of them to the GOTM setup files. Going back to the original crappy graphics would be a bug step backwards, IMHO.