Update, is that something that is still happening? Also, couldn't we add a "new game" like "splatoon 2 category extensions" that could contain ILs for OE? thanks...

I don't know much about OE as a speedrun but maybe the issue why it's ILs get little traction is because there isn't a leaderboard. I presume the majority of Hero Mode IL runners started playing because they compared their own times to the leaderboards here and found ways to improve, or motivation to climb. While it certainly wouldn't be as popular as Hero Mode ILs and it might be a little too late at this point, I think it could be nice to have and would motivate players to try playing them.

The main gripe I've picked up on that others have for OE is the Octoshot skip at the end, rather than the levels themselves, and I've tried grinding some levels myself and enjoyed it. It might just be that there isn't a platform for them rater than them just being unfun.