Finishing inside one with walls and such is a very large pain though. Drywall for example is a B!tch. You are drywalling triangles that may be 4' on a side. Of course drywall comes in 4x 8 ,10,12,14,16 sheets (and now 56" wide too), anyway you are cutting one or two pieces from a sheet and throwing about half of it away.
After a short while of this type of thing you begin to realize the delicious effeciencies of conventional construction. The construction technics and materials are so dovetailed as to become a chicken and egg question as to which let to which.
In my designs I am always exploring what can be done that has a unique design appearance without deviating too far from conventional materials and techniques. You do, after all need to be able to find people to build things, and they will be equipped with normal tools that they can buy at the lumber yard. They also will want to know that they can buy the materials there too.
And that is just the ceiling. Any wall built to come up under a dome will have to meet the ceiling. There will be no nailers in the places you want them and the top plate will be a series of short pieces of 2x 4 cut tofit the ceiling form, not to mention each vertical stud will have to be cut to length and one end will have to be cut at an angle. Figuring ten times the labor for simple things is probably not out of line. Some things will be simple ....wiring for example probably won't be too bad. By too bad I mean probably not more than twice the normal amount of labor.
Insulation too, imagine cutting fiberglass to fit inside each triangle. And there will be no ventilation of the sheathing possible, so the shingles will heat up and not last as long as normal....metal roofing? you say? good luck.
Now when you go completely over board with something like building from straw bales or making walls with wine bottles laid in mortar, (or geodesic domes) you are completely on your own, figuring out how to do each and every thing with building materials that were designed for something completely different.
That is why some folks can spend their entire lives building a house.....not that there is anything wrong with that if that makes them happy. It just won't work for an Architect or builder who is needing to make a living.
Just take a look at the last 20 years or so of Antonio Gaudi's life, building the Sagrada Familia cathedral. (He died penniless after being hit by a street car and mistaken for a bum because of his disheveled appearance).
Tom W