My 2 cents on the matter as someone who plays Civ IV GOTMs extensively:
All the HOF mods for IV include mods/features that enhance info/UI in the game without changing the gameplay. My assumption has always been that the V GOTM team want to get to a point where they can have a HOF mod for V, if Failaxis would ever open the DLL. Primary purpose is to monitor the submissions, but I assume too that they would like to incorporate some of the popular and stable info/UI enhancements with the mod - just like with BUFFY.
The point being is that one day - hopefully sooner than later - all VOTMs will be played with a HOF mod. That is, everyone will be required to use a mod. You might as well get used to it and Info Addict seems to be the perfect one to start with in the spirit of BUG/BUFFY. There's certainly no harm in it.
The difference between DLC requirement vs. InfoAddict requirement is that not everyone has access to the DLCs; thus, it puts a monetary requirement on playing the GOTMs. InfoAddict is available to everyone.
Not if everyone is required to use the mod. Then it becomes a convenience, which I feel it is anyway whether you choose to use it or not.