But you seem not to realize to what extent the Rehnquist Five use state leges as a pretext. The doctrine of deferring to them even has a name in American jurisprudence: judicial passivism. It's a subordinating of justice to power, for one thing. It also ends up privileging (by falsely pretending to equivalence) what the many cowardly, small backwards states do or don't do over what the few bold large population urban states do- it's anti-democratic by pretending to democracy. Conservative courts in this country have generally resorted to this variety of trick for centuries. What it really is is one of the three branches of government giving up its responsibility, of putting justice and standards up to a vote and in the hands of aging incumbent state legislators, who are more conservative than their constituency even. It's a very strong conservative bias mechanism.
Here in Mass. the anti-same sex marriage crowd bleated about how "voters should decide" rather than "activist judges"- but when the first polls came out showing they weren't necessarily goin to win a referendum, suddenly they weren't talking about that anymore, excoriating the state, and asking for "national consensus". Asking for federal intervention. And suing the state under the Guarantee Clause for imposing judicial "tyranny". (Yes, they got laughed out of court.)
At the time Loving v Virginia was decided (1967), opinion polls showed 90% of American voters disagreed with interracial marriage. That number was 50% in 1990. Wanna take a guess what deferring to state legislatures would have meant to interracial couples? Legalization in 1995, or 2000? (Well, maybe they would have prevented Yoko from marrying John, then the Beatles would never have broken up, and we'd be living in Paradise.) That's what the tyranny of the majority means.
Basically, there's no perfect way. Arguably the political function of the U.S. Supreme Court is not so much to decide what is just (as Oliver Wendell Holmes famously told one appellant, "This is a court of laws, young man, not a court of justice") but whether American society is ready to accept a particular increase in justice and responsibility
Here's a classical example, not even two months old, of the kind of thing that goes on with pretending that what state legislatures have done is particularly indicative. Compare Scalia's dissent to Kennedy's plurality opinion. What Scalia doesn't tell you in his claims about the national consensus, prevaricator that he is at bottom, is that the death penalty for juveniles had roughly 40% support, 60% opposition in national polling if not better.
http://supct.law.cornell.edu/supct/html/03-633.ZD1.html