Ever read White's "The Once and Future King"? In it, Merlin talks to Arthur about the whole might makes right thing too. At the conclusion of the first Harry Potter book, the antagonist says, "there is no good or evil, there is only power and those too weak to take it." Same thing there too. Interesting, yet fruitless discussion. Either you become mighty so that you can be right in your own sight, or you submit to one mightier than yourself to be right in their sight. Either way, as you suggest, "right" is subjective, when viewed along those lines.
As a Christian, I believe that, since God made the universe and me, that he knows how it is supposed to work. He's not only all-mighty, but he's also the creator and designer. It's not just because he can destroy me that I submit to him, but because he made me. That's what makes him different from a thug on the street waving a gun in my face. The thug doesn't know me, he doesn't love me, he certainly didn't design and build me. He doesn't know or care what's best for me. God does.
Now if I didn't believe in God, I would have to decide what else is right, or else doubt that anthing is right at all. If I was mugged, I really would have no basis for protest, because after all, he's got a gun. I could only appeal to an even greater power than the mugger (the police, and a judge). But if the mugger is the judge's nephew, I might not have a case.
But since I believe in God, even if the guy gets my wallet and walks free from the courtroom, God is still there who said "Do not steal" and "do not pervert justice" and who promised to take care of me while at the same time telling me not to resist one who does evil to me. And I believe he will champion my cause and even (someday) reward me for my attitude in the face of my loss.
As to God's changing his mind, I don't believe he has. He's only revealed his mind to us in different ways as we, as a people, have grown. Think of the principles at work ever since Adam and Eve that haven't changed. God is shaping a class of beings who are totally devoted to obeying whatever he says, who are not concerned for their own gain, but the eternal life of all, who are concerned about justice, who are completely loyal to God, who stand up against his true enemies, while being compassionate to the victims of sin, and so on, and who trust him above all.
You say you don't want to go to a heaven with a god who has only contempt for your feelings. I don't either. But I don't believe that is what heaven is like, because I believe God does care what we think. But sometimes, we choose to think wrong. Would you let a child or a pet of yours develop destructive attitudes if you could help it? If I had a little girl who said to me, "boys are stupid" I'd have a good laugh. But then I'd find out why she said that and try to set her straight.