As much as I like telescopes, both ground-based and spaceborne, I say cancel this project and call it a day. Build something that actually works.
They won't though because its a shelter for jobs. And no nasa administrator wants to launch this on his watch and have it fail anyways.. If it’s ever completed, the builders won’t be able to suck money from the government anymore. JWST makes more money on the ground than it ever could in space.
Unlike a planetary mission, a single astronomy mission can support many different kinds of scientists. JWST will study planets, exoplanets, astrobiology, cosmology, and stellar physics off the top of my head. So I think it's still worth the price tag and I'm sure the engineers are testing everything conceivable extremely thoroughly to give the telescope the best chance of working as planned straight out-of-fairing. If Webb is canceled or tragically thinks it's a submarine, a lot of science will be lost.
The risk of failure is an inherent part of any space mission, and the greatest NASA missions are the most audacious. The agency is at its best when it pushes boundaries. Webb may have been too complicated, but it will do amazing things that are only possible far away in space.
NASA is making sure future flagship astronomy missions won't have such a tumultuous development. WFIRST is a lot less groundbreaking and the agency is working to keep its budget close to $3 billion. The following flagship mission
is capped at $5 billion, making scientists rethink some crazier proposals. Even the cost for more modest missions is more on the ground than in space. It's cheaper to fly a mission than to develop one (at least one that hasn't been flying for
many years).
All the money JWST makes is on the ground anyway. Just think of all the families of scientists, engineers, and technicians that this mission feeds, before launch and after launch. At least the R&D money before launch is going to good jobs. Maybe some of the technologies developed will have further applications. Maybe that has already happened.