Merengue is considered a 'dreamy' (the most desirable villagers) by many Animal Crossing players. You will see her making an appearance in many pieces of fan art, and she has plenty of fan-made merch available compared to other less popular characters. Aside from having a friendly personality and getting along with everyone, I'd imagine that the reason most people want her is because of how beautiful she is. Merengue has an incredible design, and her delicious looks stand out. Food-related villagers are often desired simply for their uniqueness, and Merengue is easily one of the prettiest characters in the entire game.