As of right now, this seems to only be for high scores, which is not the point of a speedrun at all. Could we get new categories such as unlocking Rrhar'il AT from a new account or unlocking Stasis AT from a new account for example?

To add onto this, the speedruns would have nuance to them. What is the best route to take? What songs do you play? When do you start playing on IN difficulty instead of HD? (remember, IN doesn't get unlocked from the start)? Is it possible or practical to try to obtain 11 rks to unlock all INs automatically?

It's not just "play through every song and scroll through menus quickly".It can be optimized.