It's just that the king see through everyone who aspires to be queen consort already and was sick and tired of ladies trying to pin on him for his status, by being flashy or superficial or obvious trying to kiss up/ flatter him without even really getting to know him as a person or trying to really care for him in the first place and show genuineness (since everyone was just there for different political reasons).
In addition to that, FL is not just looking simple, innocent / naive or down to earth but she have sharpness, wits, wisdom plus emotional, mental and physical strength needed as consort. I bet she could somewhat defend herself in most of the situations as queen (including physical safety up to certain point). She just need to be educated for the things she's lacking and I bet she's fully ready to take on her role as future queen.
Another thing, most of the ladies came from noble families that were for their own self interest and plotting something against the king, so the king really hesitates to get a wife from those noble families since there's strings attached and possible hidden plan to put him down and take the throne. What the king saw in FL is also her character aside from not being involved in those scheming nobles.
yeah but they don hav to put down the other girls for dresses n makeup
chapter 3 and istg this man must be gay. everything abt this js rubs me the wrong way like how they put down the other consorts for wearing dresses and being girly and the trope about this innocent down to earth girl who isnt like everyone else