More series where the FL ends up with a commoner/low rank noble.
More series where there is a proper magic system. (sometimes the magic just exists are there's no proper reason why)
More series where the mc reincarnates is a body of the opposite gender. (All I know as of now is Yakuza re-incarnation).
A series where the monarchy is toppled and the beginnings of or a legit democracy are established. I don't care if it'll take forever to beat monarchy, I would like to see an otome isekai with freedom struggles, just for a fresh taste.
Can you imagine how interesting it would be for a MC to just start messing around with the proper plot of the world??? They just go like, "You know what? I have power, I have a modern mindset and I hate how this world rolls, I will change it."

Aro/Ace characters. Please, it's not hard to write someone not interested in romantic or sexual relationships. Give your mc the power to shine alone and be surrounded by close friends.