Even at the time of its release, Resident Evil 3 seemed kind of slipshod and outdated. It was an obvious sidestory packaged as a sequel, and it did little to advance the ongoing story. It was using the same muddy pre-rendered backgrounds that people were kinda tired of, along with the same frustrating and tiresome tank controls. Metal Gear Solid had come along and shown the world how amazing and cinematic a full 3D game can look. Even within the survival horror genre, Silent Hill and Dino Crisis were using fully polygonal worlds to great effect. The Dreamcast was released in the USA just a couple weeks prior to RE3, and people were looking towards the future. Code Veronica was just on the horizon, and was clearly the more interesting and promising project since it promised both new tech and new story.
None of this is to say that RE3 was bad, but it was not in a position to hold much mindshare. It released in the wake of both the Dreamcast and Final Fantasy 8.....then the next couple months brought the world Medal of Honor, Gran Turismo 2, Unreal Tournament, Quake 3 Arena, Jet Force Gemini, Donkey Kong 64, etc. RE3 is certainly remembered by fans of the series, but history forgot it because it was a very backward-looking game released in a very forward-looking time.