I’m shocked an actual quality movie like this was at one point in the IMDb 250. It’s full of nothing but trash now.
Melton1 Wanted for Pedophilia:
https://i.ibb.co/6cnPmJVr/IMG-0830.jpg
https://m.youtube.com/shorts/Zjxk307CND0

Well, I would not put too much trust in IMDB top 250 the watching of movies and casting votes for them are self-selected actions.
Some possible answers Big-city sophisticated psychological viewpoint applied to perfect(-seeming) Smalltown USA. Applied in a very subtle way.
Like a lot of Hitchcock films, it repays repeated viewing, where the viewer can make connections between what is happening and speculate about the meaning of it. For example, both Charlies are first shown as lying in a bed, and at the end Uncle Charlie is again lying in a "bed" his coffin! And at the end Young Charlie is definitely headed towards a different sort of bed - a matrimonial one. The two Charlies start as seeming to be closely connected, and at the end they have completely diverged in their fates.
Or watching the husband's face in the later dinner-table scene where Uncle Charlie is talking so gushingly about his sister and what she was like when she was young. Uncle Charlie seems to be strongly implying that his sister married beneath her - that the husband is not good enough for her. And the husband doesn't like it. Not very nice of Uncle Charlie, but is he really at fault for having such a viewpoint and indirectly spreading it around the dinner table?
It's also interesting that it takes a European upper-class horror tale, "Dracula", and re-tells it in a middle-class small-town American setting. Somewhat unsettling.
Enough of that, for now!

You've hit on one important aspect in which this film (and most others of earlier eras) differs from contemporary filmstorytelling and film technique was much tighter and moved far more swiftly. The lengthy (sometimes laboriously so) manner of telling a cinematic story that we're used to today was largely confined to a handful of so-called 'epic' films in those times. Pacing was everything, and it was fast, much faster than what current audiences are accustomed to. So they look at films from this period and feel let down that there wasn't enough story/suspense/time given to elaborate fight scenes, etc., rather than learn to
see
and adapt themselves to a different style of pace in telling a story.

I found it mesmerizing; I was in awe of it the whole time, maybe because I enjoyed the characters.
My only criticism was the very end wasn't choreographed a little longer, but that's 2014 expectations for me (where most final struggle/fight scenes last around 15 minutes it seems).