Mark 7, I see you there. I kind of think, though, that Jesus was trying to say, Hey, it's not about keeping rules; it's about the kind of person you are. The pharisees and sadducees were super legalistic and Jesus was not--he was more about showing what God was like than he was interested in rules and regulations. I think that the Bible illustrates the different ways God led his people: more strictly at first, and the stories show that they were apt to forget him in a moment; and later, through Jesus, God was showing that it's more about getting to know God personally than it's about rules. I suppose the raising children analogy would be good here: you can't always explain to a child why they shouldn't do something; sometimes it's "because I said so" and later, as they grow up more, they'll understand the explanations better.
As you might know, I'm actually an agnostic 'cause there are a lot of things in the Bible I don't get, God included. But I think that the changes in God's actions show his character, or at least that makes sense to me.