Immoral Universes

There has been a recent mini-boom in books about multiple universes, including but not limited to Parallel Worlds, The Cosmic Landscape, Many Worlds in One, In Search of the Multiverse, The Hidden Reality, and the forthcoming Visions of the Multiverse, all of which I own (or in the latter case will own when it comes out). But are these books and the ideas they represent immoral?

As someone who grew up on Star Trek and other sci-fi where parallel universes are a time-honored trope, I must say I love a good multiverse. Heck, I'm in the acknowledgments of Many Worlds in One! Thus, I don't find this whole phenomenon in the least disconcerting. There's nothing wrong with unbridled speculation; it's how more science than you'd think gets started, despite the stereotypes of science being sterile and uncreative. But at some point speculation has to be bridled and evidence must be procured, and the fact there is no evidence for a multiverse, and may in fact never be any even in principle, is definitely problematic. Thus, I can understand the consternation.

I also definitely have my likes and dislikes among the various proposals, and frankly think some of them are stupid, but immoral? I think not. No one will ever say, "Sure, I'll murder that guy for his watch and go to prison; in another universe I won't have killed him, or in another I will but won't get caught!" And there should be no limitation on what anyone, especially scientists, can speculate on and study, because you never know.