I don't follow the show all that much tbh, at least not since the end of Season 4, but it sucks how they've backed off on stuff like the Marceline/Bubblegum relationship.
Oh yeah, I had to re-watch that video on Youtube. Maybe they dropped it because the lesbian undertones were too risky and they didn't want to lose fans. It's apparent that Bubblegum likes Marceline as more than just a friend given that she wears Marceline's shirt all the time and snorts it when she gets up in the morning.
There are a lot of good ideas in the show. I would love to see more of Marceline and the Ice King. And it was brilliant when they defined gender roles in romance with Marshall Lee seducing Fionna and then having her reject him. Females always play the submissive it seems, and it was a nice feminist lesson for kids. Ice King always kidnaps them, and they always refuse, but that's besides the point.