[CamperBob2]

We launched the ISS over 20 years ago. If you look 20 years down the road from Kitty Hawk, we had already built tens of thousands of manned aircraft and fought a world war with them at that point in time.

Apparently, 20 years of progress and "promise" ain't what it used to be.

[ericd]

I think it's because it's a lot easier to go fast when there are huge potential rewards (winning a World War) and you're willing to accept fatalities (war). The rewards here are much more nebulous, and we're not willing to accept fatalities. So we go slow and careful.