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.
I don't think that's suitable for ILs, given that they use IGT, not RTA. The whole point is to use what the game gives you. Plus ILs aren't really all that serious and recording software / capture cards can be inconveniences that push people away from submitting.
You're not wrong though, my time on level 8 is def the 1:13.99 lmao
A month ago I simultaneously posted my Sunshine Isles IL WRs without video, so if that's an issue to anyone I'll go back and try to beat them while recording with my phone. I feel like asking everyone who runs ILs to do videos is quite impractical since proper DS recorders are not cheap at all and not everyone has the setup or time for phone videos. I think it's pointless to ask everyone for video evidence for these.