If people were 100% rational, would the world be better?

[vulcanlogician]

-ofc, and there's vast room to disagree and other ways of thinking about it.  I'm content to call it a selective preference so that we don't need to get bogged down with choice.  I would also suggest that regardless of whether we do or don't have free will, "choosing life" is a process of rational selection.

Choosing life only becomes rational if we "could have done otherwise."  Without it, the term rational loses all meaning.

I disagree. 

Rational agent, X, has no free will. All his actions are determined. X is unaware of these circumstances. 

So X goes around making judgments and decisions throughout his life. Some of these decisions are rational. That is, before deciding, X thinks of a premise (or premises) that he thinks are true, and uses them to come up with a conclusion. He then uses that conclusion to inform whether to do one thing or another. He did all this without free will. No incompatibilist argues that people don't think, reason, or use logic. They argue that none of it involves free will.

Other decisions X makes are not rational. Those decisions do not involve X considering premises or conclusions before making a decision. X makes these decisions based on gut, impulse, custom, or what have you.

So rational still has meaning even if we could not do otherwise.