That's a long time, especially in the harsh environment of low Earth orbit. Your auto analogy would be better if you were talking about sinking big bucks to repair a 1990 car instead of a new one. Would you spend several thousand dollars to service a 1990 car? Probably not unless it was still worth quite a bit of money like a very expensive sports car or a collector's item.

In the end, it all comes down to money. If you want more money to continue operating the Hubble, then you have to be ready to cut something else. Given the nature of the federal budget, it isn't likely that you'll get any money from other budget areas to add to the space budget, so which space programs are you willing to cut to fund the Hubble? Are you willing to cut future exploration of Mars and the outer planets? Future manned missions? The ISS (love for it to happen but it doesn't seem likely)?