MGS4 feels like an experimental MGS game, which is certainly not what someone would want to hear about the second to last game in a 5-game series. Yet so many of the elements of this game feel antithetical to what makes stealth fun, that I can't help but wonder if this was some sort of death throe for the series before PW and 5 were a thing (which isn't to mention that the story is the most "LOOK AT ALL THE THREADS WE CLOSED" plot I've ever seen).
Buying suppressors after having to scavenge for them in MGS3 is the most insane setback that that game added to the series. Buying weapons in general defeats a lot of what makes progression in this series what it is. Octocamo removes the elements of finding places to hide, and simply makes in so that crawling everywhere is the most efficient way to not be seen.
MGS4 IS a necessary step in MGS's story, but MGS4 WAS a mistake.