NASA works for the White House. There are many at NASA that wish they were building a modern replacement for the Shuttle. However, they had marching orders to instead work on other things, some of which should have no place in a research organization.

For the industry we're starting now, for suborbital flight, there is no destination, so the spacecraft you go up in has to be large and spacious. That's why SpaceShipTwo is much bigger than SpaceShipOne: It needs to be because you want those six people to be floating around and enjoying themselves.

By 1931, after a few years' experience of flying scheduled airlines, those planes were operating at roughly 600 times the safety of the space shuttle. I look at safety not in terms of fatalities per passenger-mile, but when you get in and close the door, what is the risk of dying on this flight?

Burt Rutan Quotes