'A slightly different mechanic for learning abilities' does not on its own make IX's gameplay not 'run of the mill.' I think that's a very reasonable description.

Put it this way, if someone says: "What's the most interesting thing about FFIX's game mechanics?" and your response is "Well you had to learn abilities by keeping certain bits of gear equipped for a while," that's a fairly good indicator you're looking at something without a whole lot of ambition.