The purpose of any commercial power plant is to profitably produce power. If your power system does not do that, there's no point doing it.
The cost of any power plant includes a variety of factors, including R&D. For many nations, the cost of developing commercial reactors is partially hidden in a larger military program. At a minimum, training of the engineers as part of a wider program helps, but you may additionally take advantage of things like fuel separation technologies, development of reactor technologies, and in some cases, like the USSR, the reactor designs themselves are adapted military versions.
There are only a few cases where the cost of designing the civilian technology is completely separate from the military side. Canada is one example. In this case the accounting is fairly easy; the country's taxpayers have paid about $50 billion dollars to pay one province (Ontario) to develop technology used largely only by themselves. If one adds that cost to the price of the reactors, no one would have ever built them.
So back to the story. The reason no one "builds reactors for fun" is that they cost billions of dollars. Taking an alternate technology through to production will cost an enormous amount of money. Unless one can demonstrate that this R&D will be paid off, or they can hide it on someone else's budget (like earlier programs) then any investor is rightfully concerned about the risk/reward basis. And, in spite of what the various "miracle cure" types will tell you, this is precisely what these efforts have failed to do, utterly.
And that's the state of the union, right there.
Nuclear engineers invariably blame someone else for their problems - maybe it's the "greenies" or the money men. Invariably though, it's never themselves. That's in spite of over promising and under delivering for half a century now. Simply put, no one is willing to give them more money to "play".