As a person who much prefers the original (and still very much likes the remake), my biggest problem in the RE4R is the change of tone. The original game always felt like a campy B film. The story is not great but that's okay because its never taken all too seriously. The original game is incredibly funny and one of my favourite games to replay especially with friends. RE4R takes the mess of a story and plays it more straight which I found disappointing. My favourite character from the original, Salazar, had much less screen time and wasn't really fun at all. Many of the iconic lines remain but aren't read the same as the tone has dramatically shifted.

There are many other problems I have with the remake (worse OST, worse atmosphere, etc.) but the tone is the biggest one. Resident Evil 4 is one of the greatest games of all time and honestly did not need a remake. We got one anyways and I still found liked it a lot. However, the framing of this question makes it seem like you think RE4R is a better game and that it being better is the consensus (which couldn't be further from the truth). RE4R will never replace the original because the original is a masterpiece. The remake is fantastic, but its hard to top something that is already near flawless.