I think it would be interesting and it would definitely be fun for people who prefer to communicate with their creative side, but I also think the idea of spreading abilities around different ranks would not work out very well. In community based games, extra powers for certain players tend to break the atmosphere for many, cheapen the experience for some, and can also encourage cliques or player worship (for favors, etc.). I think a better solution for subscribers would be to give them extra items in order to ease their workload in the game, but not extra abilities that set them apart from the mortality of other players.