Why heat water to heat concrete to heat air? Why not just use an electric heater to heat the air?
Because heating the air is not what radiant is all about.
If you'd ever lived or worked in a radiant heated space you'd know the difference, and know how comfortable radiant is.
I heat my shop with radiant powered by electricity. Is it cheap?? No, but sometimes it's not all about cheap. It's comfortable, there's no drafts, there's no fumes, there's no flame, there's no pilot light, no flue through the roof. I don't have to worry about fire, chemicals, fumes etc. My feet are always warm, I work in a T-shirt with the thermostat set at less than 60 degrees. My shop is more comfy at 60* than my house is at 70*.
Would it be cheaper to burn natural gas?? Yep, but by the time I add in what it would cost to get it hooked up and switch over all the equipment(most of which was there when I moved in), the payback would be rather long.
Maybe some day I'll switch fuel sources, but it'll always be radiant.