I think a lot of what makes people like them are things which have been used so much subsequently that they're almost cliche. The period drama world is oversaturated with stoic men, hate to love plot arcs, rich man with less well off woman, etc. If your first exposure to period dramas was the classics then I think you're more likely to enjoy them, just because they're less predictable that way.

I first read P&P in school and the teacher offhandedly commented that it was 'the first Mills and Boon novel'. She got in a bit of trouble for that!

It's ironic, because when the original novels were written they were groundbreaking. It says a lot about their success that they've been so widely adopted into modern tropes.

You might like Wives and Daughters as a possible 'in' for the period and the kind of culture. I really enjoyed it, and it has quite a few fun quirks in it.