The separation of UI and Sim layers for modding is a key feature of SupCom and one of the things that makes its UI so advanced. People should be free to use whatever UI mods they think will improve their experience or effectiveness, including coding their own private UI mods.
UI mods should be allowed and part of the game, and if some people are losing an advantage by not using them, then the problem is education, not UI mods.
And if some people know how about the existence of UI mods, but are unwilling or unable to use them effectively, then that's a player skill problem, not UI mods.
We can only decide that UI mods are a problem when their use is universal and we see that the entire game devolves into some unwanted state. That's the time when access to certain functions/data should be closed off to the UI layer, or certain UI mods banned, etc.