It's a huge deal! huge! Shame on you for having a new idea :P
It can be rolled thinner, but if your recipe isn't just right, or if you don't handle it just right, it's really hard to use is all.
I've made one with the same sort of 'flowers' just not a dome, used fondant on IMBC, nothing melted or drooped. I agree with not letting the fondant get too hard, otherwise they would be a nightmare to apply to the cake.
Unless you serve the cake chilled though, when you cut the flowers it will get messy, they push into the buttercream and kind of slide about. I like the idea of taking them off and serving them on the plate, would be pretty.