Complaining that Indianapolis lacks a subway or a ski resort or a beach is like buying a Suburban and complaining about the mileage. It is what it is, which is mostly very good.
No culture: Wrong. Visit the Indianapolis Museum of Art, the Indianapolis Symphony Orchestra, the opera, the ballet, the Circle Theater, the many universities and colleges with first class cultural opportunities. If you're missing the culture here you aren't looking.
No skyline: Look at the pictures.
No rivers, lakes, greenspaces, etc.: Wrong. The White River flows through the city, as does the Central Canal with miles of crushed gravel path. There are many more miles of connected rail trails. There are two huge lakes on each side of town, one that is home to a lot of motor boat activity, and another that sees a lot of sailing and rowing races. There are many large city parks. And just an hour south is Brown County State Park, home to some of the best mountain biking east of the Mississippi. Look it up.
No diversity: Wrong. Come and look around. If by diversity you mean, there aren't as many jaded too-cool-for-anything-but-NYC posers, then yes, Indianapolis may not be that diverse. But even that population is growing, based on the increasing number of bearded hipster guys riding single speed bikes in girl pants. Even these guys, however, fit in with the rest of us nice, normal, and well-adjusted people.
The bad: It isn't New York or L.A.
The good: It isn't New York or L.A.