For me it's a feeling of pity. As one of those who haven't watched Casa, it had felt rather unfortunate watching Ronnie trying to set the stage for the Casa Harem.
To attempt to paint a picture of the contrast between the Loud and Casa Harem to me. Let's say in a theoretical Adventure Time game where Finn has a choice between two Harems. On one side you got Princess Bubblegum, Marceline, Huntress Wizard, and Lady Rainicorn. On the other side you got Flame Princess (Like Ronnie she's still a popular character] but the rest of the line up is Bee Princess, Toast Princess, and Elbow Princess. There's nothing wrong with those characters. It's just a unfair match-up.
Which brings up another unfortunate thing on my mind is that at the end of the day, the Casa Harem is the 'best' it could be. There really isn't much other options even if Ronnie had wrangled someone from Royal Woods. Part of the reasons is touched on below. The majority of fan favorite non-Loudcharacters in Royal Woods are 99% fanon content. Even if it was somebody who shows up often like Stella. Stellla is such a nothing character that the show runners would rather invent a new girl for the friend group over doing anything with the character.
An amusing thing is that a more fitting analogy would be The Loud House itself. One of it pitfalls is having way too many characters to divide screentime with. Leaving people more prone to annoyance when an episode comes along that they aren't there fore. Case in point the future 'Hamalot' episode. Some people didn't come to the Loud House because of this Lance character and his family. But more than that, they're annoyed at having an episode slot be wasted on them. Now they have to wait even longer for an episode that they like.
