“the Court let stand Section 2 of DOMA which is a significant part of it. Section 2”
Don’t be fooled by the Court’s decision. It did not affirmatively “let stand Section 2” — Section 2 was simply not at issue in the case. I think the current Court would toss Section 2 in a second, if it was presented with an opportunity to do so.
My one reservation concerning Section 3 is the following. When the Supreme Court decided against the Mormon practice of polygamy when they decided Reynolds v. United States, 1878, since the 10th Amendment did not apply because Utah was still a territory, not a state, the Court applied English common law which which evidently defined marriage as a one man, one woman union. Given that common law is referenced in the Constitution's 7th Amendment, I think that the federal government should still be bound by that precedent today with respect to federal marriage policy.
Also, note that DOMA Section 2 is reasonably based on Congress's Full Faith and Credit power (Section 1 of Article IV), power delegated by the states to the feds to regulate the effect of one states records in another.