My guesses: - due to the time between the start of the project and the end, enough time has passed where there are sufficiently new advances in science/tech/ro

My guesses: - due to the time between the start of the project and the end, enough time has passed where there are sufficiently new advances in science/tech/robotics/etc to open up new possibilities - a second one will probably still cost >10% of the original - a second one wont yield enough benefit to be worth it like...the JWST isn't anything like hubble, and can do things that hubble cannot. So it's not like a fleet of hubbles would equal one JWST or something.