The thing is, when one holds up a line of text and interprets it literally in order to poke fun at people who one thinks take it literally, you're being as simplistic in "Bible interpretation" as the people ridiculed.
To poke fun at people, you're dead right. There's no call to do that.
But to point out the inconsistencies and plain wierdness in their beliefs, it's definitely fair game. The Creationists (who believe in the literal truth of Genesis, and of whom there are a goodly number) are a particular case in point. Genesis is just a Babylonian folk myth, and as such has as much relevance as Greek or Roman mythology. There are definitely parables/fables in there with morals for what you should and shouldn't do. But to say that this is the literal truth is daft - it's like taking one of Jesus's stories and saying "there was a real person to whom this happened".
For the Creationists, the literal truth of Genesis usually follows from a belief in the literal truth of the whole Bible. Anti-homosexuality campaigners often also quote "thou shalt" or "thou shalt not" from various places. For both of them, various quotes illustrating God having a betting contest with the Devil over Job, or Exodus with God forcing Pharoah not to do as Moses asks and then killing the Egyptians for doing what God made happen, or the various acts of genocide on the way to Canaan, or the various dafter proclamations of Leviticus - all these give a good idea that whilst the Bible is a source of morality in places, in others it's basically a snuff movie.