Maybe that's just what happens when a series has run its course? Resident Evil started in an era where gaming had made the seismic shift to 3D, and was able to explore new concepts and gameplay elements that had never been done before.
What else can you do, really? RE4 made the bold choice to shift the genre, but eventually, there's only so many ways you can tackle the same concept. Most modern survival horror games thrive on isolation and a feeling of helplessness. That was never so much Resident Evil's jam, and while it worked for a while, maybe there just isn't a place for it in gaming right now?
That being said, I think it could still get some run if they lean more heavily into the VR aspect. It's the perfect fit, and RE7 was a good start.