To be honest, I suspect that someone reading Pride and Prejudice _after_ reading a bunch of ao3 stuff is going to suffer from https://tvtropes.org/pmwiki/pmwiki.php/Main/SeinfeldIsUnfunn... to an extent; part of why was significant was just in establishing a bunch of tropes which have now been absolutely _done to death_.
I've made sure to reference "historical significance" when referencing P&P and the Cabinet for this exact reason. I think every classic undergoes some amount of 'rot', but I've also found a lot of classic to be perfectly enjoyable if you allow them some slack.
And, not to insult fanfiction writers (I've been known to partake), but I would guess Jane Austen still writes a better broody man than most of them... although probably not all of them. That's a secondary consequence of simply having more people partaking in art to begin with: the more millions of artists you have, that many more one-in-a-million geniuses you're bound to find.
