SCOTUS reached the merits because they wanted to make a policy decision. The current court is making radical changes to established law, such as last term's decision to throw out much of the VRA simply because the justices felt it was too old and no longer needed. (It was re-authorized in 2006.) Allowing judges to throw out the decisions of the legislature or executive on major policy questions, with a flimsy and partisan legal basis, is not a sustainable way to run a democracy.