We certainly can't be enamored of the class system, as every hero and heroine in that era defies the caste system. Heroes are portrayed as rakes who are better than everyone else because they are not hypocrites (it's okay to be immoral as long as you are upfront about it and have a terrible mother to justify your actions). Heroines treat the hired help like best friends and these hired help stay on despite not being paid because they love nothing more than to be loyal to the heroine. So, no, aristocracy is bad.
Is it the cultures and virtues of being English? I guess, but we all know what happens the moment we introduce an American or a Scotsman into the mix - all of a sudden, those characters become the pillar of virtue while everything English becomes even ten times more boorish in comparison.
Or maybe we love the clothes? But then again, our heroines tend to delight in forgoing corsets and what not, often making a statement about how restrictive women's clothes of that area are. Men deliberately avoid wearing wigs or codpieces - breeches are okay because they show off those lovely muscular thighs and the bulge of manliness - preferring instead black like a GQ version of a Goth. They don't have snuffboxes, they only reluctantly let their valets dress them up, they dislike buying clothes of their time. So it's not like fashion is portrayed as an attraction in these romance novels. Both the hero and heroine hate it.
The ballrooms? Almack's? Both the hero and the heroine hate them. Those ballrooms are hunting ground of vapid debutantes, heartless married women looking for adulterous escapades, and hateful gossips! How glad are the hero and the heroine to finally avoid attending those TEDIOUS things!
So, honestly, what exactly are we supposed to like in these historical romances again? The accent?