But playing the devil's advocate - I think that having the shuttle really did help with the HST. The ISS still has the potential to help with future mission staging and "might" actually produce some real science.
My turn to play devil's advocate. No question in my mind that the HST is the single most important astronomical instrument ever built (except perhaps for Galileo's little refractor). I say this both for the quality and quantity of data it's returned and for its ability to connect with a larger public. But HST was designed to be launched and serviced by the shuttle. Problems with the shuttle caused HST to be launched several years late, and current problems probably mean that Hubble will die too soon. Let me hasten to say that those servicing missions have been the high point of the shuttle's many times aloft. The question we can never answer is what kind of scope would HST have been with no shuttle. It's fun to speculate. We'd still have had heavy lift capability, so we could have gotten something up. Perhaps we'd have built a platform that was serviceable by robot (something HST isn't). Or perhaps we'd have launched new scopes every few years. That may have actually been the more economical way to avoid wear, tear and obscelescence. I remember one of the early shuttle missions where they rescued a satellite after its Pegasus booster had failed on a previous shuttle release. NASA was boasting how the shuttle had saved the satellite, when the shuttle-based launch had been the initial reason for failure. They could have sent the thing up on a Delta for a quarter the money and no risk to life. The Trib has an interestingly skeptical editorial today about the new NASA direction. In essence, they like the change in technology, but they're doubtful about the financials. While they're correct in their skepticism, the current situation is untenable, so change is absolutely necessary. I'm delighted to see the human space program go back to moving humans and the cargo business go back to unmanned rockets.