Charles Krathammer has a column about why Chief Justice Roberts ruled the way he did:
Roberts, custodian of the court, acutely aware that the judiciary's arrogation of power has eroded the esteem in which it was once held. Most of this arrogation occurred under the liberal Warren and Burger courts, most egregiously with Roe v. Wade, which willfully struck down the duly passed abortion laws of 46 states. The result has been four decades of popular protest and resistance to an act of judicial arrogance that, as Justice Ruth Bader Ginsburg once said, "deferred stable settlement of the issue" by the normal electoral/legislative process....
There's only one way it can be overturned. The same way it was passed — elect a new president and a new Congress. That's undoubtedly what Roberts is telling the nation: Your job, not mine. I won't make it easy for you.