I don't know much about architecture, but a building is generally bespoke. It's made to a specific physical location and has to work in its surroundings and be built to local regulations. From that viewpoint I can't really judge how much value the blueprint actually has and therefore if it matters who "owns" the IP. The architect has done real legwork to bring that specific building to life and anyone else would need to redo much of it to copy the result.

Any human effort can be a creative artistic expression. You could mass produce a jacket or a hand-stitch an equivalent jacket and both will be warm. You could code a subtle and elegant CMS for a website or use some pre-built solution, both will deliver the same content. The difference is, people will laugh you out of the room for trying to patent your home stitching technique but nod and clap when you put a license on your code.