I think adding individual stage runs could be interesting and I would like to see it added.

Most stages are very short, I don't see why you would want that

I see both positives and negatives to this

For Positives, I can see this doing well with the small community and that certain ones, like stages 9 and 15 would be great individual stages. This can also offer an alternative for players who want to focus specifically on one level.

For Cons, I also see multiple levels that can be beaten in less then a second if you do the previous level a certain way (Ex: 26). We can mainly combat this by forcing the player to not exploit this and to start the level normally and deny any attempts that use previous levels as an advantage (like NYZ or NYZ2). Even with this in place some levels wouldn't be good for individual speedrunning.

There also bugs that let you finish a stage in 1 second

I'd love to add the individual stages, not all of them, but totally certain stages.