Pro-gay spins on the meaning of the 14th Amendment's equal protections clause aside, why should the Supreme Court get involved when the answer is obvious? The states have never amended the Constitution to expressly protect so-called gay "rights."
Consider that the states never ratified an amendment for the regulation of drugs as we have with the War on Drugs like they had to do with alcohol. Instead they rely on precedent
(*spit*) of things like Wickard and Raich — it is in the supporting of the War on Drugs that we have the acceptance of the NSA's domestic spying [legally speaking] and the erosion of many other legal rights. (According to my count the War on Drugs has had deleterious effects on six or seven of the Bill of Rights's Amendments.)
In short, the Supreme Court is not above issuing rulings supporting "current practices" even if they are in direct conflict with the Constitution.