That's just really, really weird.
How do other things made after alter the original in any way?
I was never a fan of Halloween to begin with so I can't comment on that, but the fact that all the sequels and prequels to the Exorcist were schlocky B-movies at best in no way changes that the original was a cinematic masterpiece.
I could get maybe saying that lesser remakes could alter your perception of the original if you had never seen the original as if you already have negative feelings about something because the sequels you had heard about or seen were terrible that could create a preconceived notion about that original...but if you've seen the original and you liked it that cannot happen.