I'd also like to see this implemented.
My LS does pretty much everything together, and we like it that way.
But very often we are only 4-7 people online at once, and we don't want to be forced to team up with strangers who may not know how to play their class or how to react to bad habits we have.
If it's too much of a hassle to implement new light party content, I think SE could and should just allow us to do the content already ingame (like Ifrit) with a party of 4-8 people instead of being forced to have 8 people.
If we wipe, well, that's our problem.
But we are confident enough to think we can do it with 7 people instead of 8, too>

We also know this is technically possible, because Toto-Rak was for 4 people before, too, and they changed it so it's 2-4 people now.