In theory I'd agree with you. In practice so many people hold so many beliefs directly contradicted by completely unambiguous evidence that "it fits" is already a substantial step ahead of many individual's views. But more importantly, it's important that some people can and do hold divergent views rather than everybody all adopting the one most probable view.

The reason is that most probable does not mean right, and those who hold divergent views can help progress society by pursuing research in things that others would find to be a waste of time. In cases where they happen to be correct, the introduction of compelling evidence (beyond "it fits") can help reshape our understanding and ultimately change what the 'most probable' view is!

A tangent on a tangent, but if people required their views start with the standard of "it fits", I think that'd be one giant leap forward for society as a whole!