Ranma 1/2 has always inspired fanfic writers - this could be attributed to it, much like Sailor Moon, being part of the "perfect storm" of hitting the English speaking world in an era when anime was new & exciting and the internet was beginning to fully take off. But I like to think that a significant portion of this reaction stems from the fact that Ranma 1/2's setting and characters are full of potential that the canon story doesn't quite exploit, for whatever reason.
A perfect example of this is something relating to Ukyo: in fanfiction, it's a common scene for Ranma to come to Ukyo as a kind of confidante - he grabs some food and vents about his troubles, or uses her as a sounding board for ideas, or otherwise just hangs out with her and talks, with Ukyo encouraging this as a way to showcase herself as a superior fiancee choice. Now, this kind of scene makes a lot of sense; it's a common use for Ukyo's character archetype of "the childhood friend turned would-be lover" in other romantic manga, it showcases what makes her unique compared to the other fiancees, and it encourages the reader to think that "maybe Ukyo is a good match up" and/or "maybe Ukyo has a chance". But this scene is completely fanonical; it never happens in canon, and it can't, not just because of how private and reserved Ranma is depicted as being, but also because it would go against the manga's intent, which is to portray Ranma & Akane as the only "real" couple, with everybody else just being an obstacle to their final love.
So, in your opinion, what are other little or major things that Ranma 1/2 could have included, and which could have been interesting, but it didn't for whatever reason?