Ray Wilson has more in common with members that started with the band, than he does with major contributors in the band. His legacy is similar to Chris Stewart and John Mayhew. They are footnotes to the history. They played on albums that generally are considered to be less reflective of the Genesis music that fans embrace in their catalog. All three have contributions that also less significant than other members. Musically, their impact was not as important in regards to the band's history. One can counter that Anthony Philip's tenure you was similar, however Anthony Philips is credited for pushing the band in the direction we have come to known as Genesis. This is not a trait associated with other members of the band including Wilson.
Wilson is recent in the band's history. While their are critics of Mike and Tony's decision to end their relationship, Wilson does profit from the timing of his tenure in the band. Since his departure in the late 90's, he plays a lot of Genesis music as part of his catalog. His counterparts with similar histories were unable to profit from their experiences as Wilson does today. And this may be his biggest contribution to the band. Similar to tribute bands like the Musical Box, he keeps the music relevant for new fans to discover. This might be Ray's greatest contribution to Genesis. Musically, he is still a footnote in the history of Genesis, and not a major contributor, which is why fans are so divided about Ray Wilson's place in Genesis history.