Because it's one thing. What if he's better than you in every other aspect?
Again, I believe it makes me better person than I would be without it. Not better than my neighbor.
How can you judge that you're better than your'e neighbor just because you keep shabbos and he doesn't?
We have different definitions of good people. Mine is very black and white. Without being judgmental.
Btw, If you teach a child that EVERYONE is good, because there really is no good or bad... IE You can be a good reform Jew, a good gentile, a good pot dealer, a good gay person, a good orthodox rabbi etc. Then IMHO the child is lost in a politically correct mad world.
Orthodox Jews are guided by the Torah subject to the interpretations only of gedoley Torah, (not any feminist wannabe)for the definitions of good or bad.