You're right that thorium can't be enriched because there's only one isotope. It needs to be bred to Uranium-233 to work. However, breeding has been more expensive and costly than enrichment, and this is the crux of why thorium use wasn't expanded in the past. To breed thorium to uranium-233, you need a breeder reactor, and you need a chemical separation facility. Together, these are more expensive to build and operate than a centrifuge and simpler non-breeder reactor.
In this sense, I disagree that the process is orders of magnitude simpler. I'd argue that it's the opposite!
The idea that thorium-derived material can't be easily used to make nuclear explosives is an unfortunately persistent myth. You can easily make very nice weapons material from thorium. As the Livermore weapons designers once said:
"If today's weapons were based on U-233, [we] would have no interest in switching to plutonium" [1]