In fairness I think it's arguable whether the reason those races are popular draws from cute or more conventional proportions. Lalafell I definitely think cute is why they're popular, but when it comes to miqo'te, hyurs, and au ra of both genders and subtypes I think this might be some uncanny valley principles at work.
Lalafells don't look remotely like they have realistic human proportions and don't aspire to it. They play into soft features and big eyes (reasons people feel affection/protectiveness for babies) and that brings them a measure of popularity. Roegadyn and elezen both are closer to human proportions but without the cute buffer and while having certain features that read as humanly impossible, such as head-to-shoulder ratio. This can be balanced visually, but alienates some players who are't looking to do that. Hyurs, au ra, and miqo'te basically read as either human or human with some exotic features attached.
