Excellent stuff! I admit I never heard of or saw it until I moved to the UK (along with Don't Look Now come to think of it!). The songs and authentic British traditions really do sell it you are right. I don't think its influence can be overstated, yet many people watching Midsommar or other films that you mention probably haven't even seen it. I watched the remake in the same vein I watched the Psycho remake, I think Nick Cage's Wicker Man is worse though!