I read the book, well short story really, by R. Matheson years before seeing the “Omega Man”. I was disappointed by limited scope of special effects, and cheesy makeup. There is something to be said for modern special effects. Of course you can remain a purist. Since Nosferatu was made in 1922, Dracula (1931) is just another remake and not worth seeing. No point in ever having enjoyed the movie Destination Moon (1950) since French made silent movie A Trip To The Moon (1902) is available.
All kidding aside, some remakes do really suck. Some are much better than the originals. One thing you can count on more often than not is that the book they were taken from was better. I just hope and pray no one EVER tries to make a movie version Battlefield Earth again.
“One thing you can count on more often than not is that the book they were taken from was better.”
Only exception to your rule that I know of was “Jaws”. The movie was much better than the book.
And frankly, modern direction. The old actors were very good, but the scifi and horror directors were a joke.