I agree that specifically roller skating games are few and far between, but skating (skateboards) are similar enough to utilize the same general controls. Its the difference between a motorcycle racing game and a car racing game. They still control the same way.
I have been making games for a long time and I have seen multiple good games get no traction because of "unique" controls. I really dont want to see that happen to you. BTW, I dont think there is anything wrong with having unique mechanics that have non-standard controls. Its simply the primary control method of moving around should be what people have come to expect. If you are Nintendo or a very well known developer, you can get away with doing something really different. With the game industry as flooded with content as it is now, players have about 3 min of attention to be immersed into your world before they move on to any of the other 10,000 games that came out this year.
Can you think of successful indie games that heavily innovated on basic controls?