NASA has done some very impressive stuff it's true. But if you consider that it went from a standing start in 1958 to moon landing 11 years later, it ought to have done a lot more in the 40 years since then.
In the years since its Big Funding Crash, NASA has gotten good at robotic exploration, planetary science, launching satellites, and other interplanetary odd jobs that are impressive and important but less epic than the moon landing. They should keep doing what they're good at -- robotic exploration, space science, propulsion technology, etc.
But designing manned spacecraft that are safe and efficient at scale is something they've never really been set up to do. That job should be left to groups of people with the right incentives built into their organizational DNA:
http://en.wikipedia.org/wiki/SpaceX
Hopefully, they'll have more competition soon.
It takes thousands of people BECAUSE of all the advances in technology and automation and robotics and computers and so on.
I'm just a casual observer and fan, so I don't know if this is actually true, but the Mars rover mission seemed 10x more complicated than the Moon landings. And that's the last one... not the upcoming one that looks even more awesome.
NASA is a poorly run, oversized govt agency, but give them credit for accomplishing some of the most amazing feats humanity has ever seen in recent years. And you know what... maybe that's what it takes.