I think that switches (even only once) can be done really well, and show a new side to the relationship. The ( former) uke is given power in a different way and (former) seme's face is usually super hot. I am not saying the should be a switch couple, I am merely saying I would love to see a one time deal that looks really hot.
I think some fans want to see it because they are horny lol but I'm also glad a switch did not happen, we got to see both their sides without having to switch places. I also love that Fumi is the Seme without having to switch since cute semes like him are rare here. I like that he is the full on seme without becoming bottoming.
I wanted to see the main couple switch !
The seme even offered to bottom! Why must you turn him down! It could have been soo hot (〜￣△￣)〜