When we build prototypes and stuff. We can calculate for them and we have the ability to run computer simulations and can create them but additional real-world testing never hurts. Also, hot knives from the fingertips sound kind of cool.
I'm sure there are. I'd be surprised if no one else had turned into a skeleton before. Alphys is a scientist and I can confirm that we mostly survive on junk food. Also she's really into Japan.