The thing about the 5-man team from POM through SSOASS is that this was the first stable lineup the band had for years and years, the first one that released more than one album, and the one that established Maiden on the international scene. Therefore it will always be considered the "classic" lineup.
You have bands that stayed together with the same lineup from start to end, and bands who changed members between every album, but regardless of that, every great band has an era that was considered their "classic" one, and it is usually defined by when they started creating what is seen as their best material. For Maiden, that was the 80s, even though the new material has gone down well.