Why Convert If a Righteous Gentile Is Already Equal Before G-d?

If a gentile can fulfill G-d’s will in their own way, what’s actually gained by converting?

Q. Why is there conversion if a gentile can make Hashem happy in his way which is equal to a Jew’s the only reason I can find is that they want to do more mitzvot.

G-d is perfect and doesn’t “need” anything. We all, Jews and gentiles, do mitzvot because of the eternal G-dly ideals involved, that we totally identify with. Nevertheless, the Nation of Israel has a unique role as the “Light for the Nations” to bring monotheism, morality etc. etc. to the other 99.8% of mankind, gradually raising them little by little to be that much more G-dly and good. For this unique role, G-d gave us many more obligations, both individual and national, and also runs our history in a totally different, often more difficult, way. Gentiles, who comprise almost all of mankind, are meant to observe the 7 Noachide laws, and there’s no reason to do more, for that’s exactly what G-d wants of people. Nevertheless, if some of them individually, adamantly wish to join the Jewish Nation, we are not racist, so how can we say no?! Nevertheless, there really is no reason for them to do so, for G-d loves them as He created them!