I've got it right, BT. If the Constitution protects gays from discrimination, it protects them from discrimination in marriage and even if states have the right to regulate marriages, they must ALL do so under the Constitution, i.e. respecting the Constitutional rights to same-sex marriage that its defenders claim to have found in the Constitution.
If the Constitution grants the right to same-sex marriage, then it is a right which would apply across the board to all states. None of them could, under the guise of regulating marriage, abridge that right. So the concern (that Hawaii not be forced to emulate Massachusetts) is totally bogus - - if the right is already enshrined in the Constitution, Hawaii could not do other than follow Massachusetts. If the right did not exist in the Constitution, all states would be free to legislate as they saw fit on same-sex marriage.
The only purpose the amendment to the Constitution could possibly have would be to "clarify" the Constitution by eliminating the possibility of its being interpreted in such a way as would prohibit any state from preventing same-sex marriage.