Put it this way: the consensus of informed scientists is that minor changes in physical constants would make any kind of life they can conceive of, esp. intelligent life, impossible. In fact, they would make our universe impossible. If there are completely different forms of life possible, life which could exist in some of these alternate universes, their basis is completely unknown in terms of present knowledge, so talking about them is essentially metaphysical, not scientific. And we all know how objectivists, logical positivists, and militant atheists hate metaphysics. It's like talking about Santa Claus or the Pixies, for Darwin's sake.
One can, however, plug different values into equations which are parts of well-supported physical theory, and conclude that they would produce a universe with certain characteristics; characteristics radically different from the universe we see.
Daddy: "We all know how objectivists, logical positivists, and militant atheists hate metaphysics. It's like talking about Santa Claus or the Pixies, for Darwin's sake."
Boy: But why is the sky blue?
Daddy: The logical naturalistic materialists who have Nazi, Communist, Hitler and Stalin and MaoTsetung who killed millions of people.
Boy: But why is the sky blue?
Daddy: The Bible says to accept Jesus into your heart. If the Bible says the sky is yellow, the Bible is right.
Boy: But the sky is blue, isn't it?
Daddy: What god says is true. Satan makes you think the sky is blue.
Boy: puzzled look, and wondering if anything about skies makes any sense now.