Rationalia is still ruled by political ambition which will twist things. But even if not, "perfect rationalism" can yield terrible results.
Consider: What if the FDA, by making excruciating demands for safety and efficacy, delays (or halts) useful drugs? A drug that helps heart disease, delayed 5 years, could cost hundreds of thousands of lives. Meanwhile, how many lives does the FDA save over using people as guinea pigs? Nobody wants to get sick or die being the test subject, but it is at least conceivable a "forge ahead and pull back only when problems seen" strategy would, net, save millions of lives, year upon year.
And global warming? What would slowing the economy 10% cost, say, over a century in the rate of technological development? I can easily see doing nothing, and moving in from the sea over 100-300 years, ending up with more, happier, healthier people in 300 years than current sea levels and technology 50 years behind where it otherwise would be.
None of this, and many others, including currently unforseen effects, unfortunately are taken into account in "Rationalia".