Thats rather egotistical of them in a way. What I can't stand is addon makers turning their .cpp files into .bin files. Sure it compresses it and improves performace, but shit. When a certain maker of a certain Hk weapons pack makes pistols that fire with the velocity of paintballs. I feel this uncontrollable urge to fix it and play the mod to my satisfaction. Or gouge my eyes out after witnessing such a travesty.
I can see model makers not wanting people to steal models and then make addons out of them without permission, thats understandable. Still its not like they can sell the things they make for OFP so why not let people change their shit around and be happy as long as they don't release it without consent.