During the 1950s~beginning of the 70s, the "space race" between the US and Russia caused some very ambitious missions, such as the Apollo program. This was a "race"- seeing which got farther. America won in the end, but then NASA decided that studying our own planet was more important than going to other wonders of space, at that age. Thus, the space shuttle was born. It was a revolution. It could be reused many times, and there was even a cargo hold to bring heavy equipment to orbit. There was an airlock so everyone didn't have to change to spacesuits every time there was an EVA.
But a common joke says "the space shuttle's goals were to make spaceflight cheaper, safer and as ordinary as driving to the mall. Hey, one out of 3 isn't that bad"
I think this actually sums up the shuttle program. Not that I think the program was a failure, but that it wasn't fit for the trend.
(wonder if the use of the past tense "was" was a bit too early; the mission's going on right now)
The shuttle was wonderful. It was a cutting-edge multi-purpose vehicle. But with the International Space Station, the multi-purpose vehicle looked less like the wonder it is but more as a camping car towing a huge trailer. And it was used for just a few days to get to the destination.
In fact, all manned spaceships became just a 2-way ride to and from the space station. So the shuttle wasn't really fit for the type of space explorations we do now.