To be frank, masteries are boring
We have so little options to pick in masteries. I'm sure everyone wants more options in what they can do that makes them feel more "unique". This guy got so many upvotes (http://boards.na.leagueoflegends.com/en/c/skin-champion-concepts/9r9v2RR9-complex-mastery-system-a-fan-project-100-hours-of-working) because people loved the idea of having so many options to pick. You only have 3 trees to choose and you will only be utilizing 2 of them. That's pretty boring right there. This guy made 12 different ones. That's really interesting, don't you think? We actually have something to choose from. I know Riot is changing masteries and runes next season, but they're probably not doing something as cool as that fanmade system. But maybe we can make them, considering they are adding a sandbox, solo queue and other stuff.