Resident Evil: Code Veronica is not Reisdent Evil 4, although it is the fourth game in the RE series. In some ways (like the way in which it actually continues the story of RE2) I prefer it to a tepid narrative exercise like RE3. In other ways I find it undercuts the apocalyptic anxiety that even RE3 managed to maintain. Code Veronica is the point in the series where the shift from horror to action--at least in terms of characterization--happens most clearly. It is when the protagonists cease to be normal people and become action heroes.
I find it significant that Code Veronica was the first Resident Evil to be released after The Matrix (in March 2000). Claire, whom we last saw as a modestly skilled biker in RE2, inexplicably behaves like Chow Yun-Fat in the opening cinematic, dodging helicopter bullets and obliterating a room full of security guards with her powers of slow motion. Of course, it wasn't until RE4 that these sorts of action hero acrobatics made it into gameplay, but they are first introduced into the fictive universe of RE in Code Veronica, causing an unmistakable tonal shift. The shift moves the series away from the horror film roots of George Romero and towards the big Hollywood action of Michael Bay or the Wachowski Brothers. It's not about regular people trapped in a horrifying zombie outbreak anymore. It's about secret islands, villains with master plans, and ass-kicking heroes taking them down. Oh, and there are some zombies in there too.
To be fair, Code Veronica only embodies this in the cut-scenes, with the gameplay remaining the slow, Romero-esque suspense of earlier RE games. This gives the game a weird tonal contrast, between the action movie plotline and the horror movie atmosphere and pacing. This is partially what makes Code Veronica more interesting (at least story-wise) than RE4, since it seems to exist in some awkward purgatory between Hollywood gloss and indie grit.
It's true that RE has never been fully an imitation of Romero. There has always been a layer of Hollywood action mixed in with the more Romero-esque elements. Both RE1 and 2 end with "escape before the explosion" sequences, both which seem lifted directly out Aliens. Both RE1 and 2 tend to leave their zombie movie conventions behind at their most climactic moments as well, opting for spectacular last boss encounters with creatures that are anything but zombies. But still, it's worth pointing out that even in these moments the feeling in RE1 and 2 was of more or less normal people being set against these odds. Claire is just a biker looking for her brother, and Leon is just a cop. Neither of them know kung-fu, neither of them can jump or flip--in short, they are only as good as the weapons they have... much like we might imagine ourselves in similar circumstances. Chris and Jill in RE1 are similar, even through they are the members of a supposedly "elite" police unit. The S.T.A.R.S, at least in RE1, are not super heroes. They are basically no different than the S.W.A.T. team in Romero's Dawn of the Dead: real people without super powers. The only difference between them and zombie food is the fact that they still have some bullets left.
In the early Resident Evil games zombies were the great equalizer that brought everyone down to the same level. RE2 suggests there's not a damn difference between a biker and a cop when it comes to being trapped in a city overrun with zombies. It's exactly this sort of humanizing subtext that gets gradually eroded over the course of the series, until we finally arrive at Leon in RE4 who can dodge lasers like Neo.