B-52s are still flying and they are a bit older. Yes, same parts deteriorate but they know what to replace. It's not as if they totally ignore everything when they prepare for a launch.
I have been as proud of the space shuttle as anyone. But, this isn't a B-52. When a B-52 loses a system it is usually not flying at 20,000 MPH in the middle of nowhere, and the crew always has a chance to eject. But, more to the point maintaing a B-52 is a heck of alot cheaper then the shuttle program. It was a good program; but do we really need to continue to invest in three old shuttles?
The B52 has redundant systems. For the first two minutes of flight the Shuttle is a projectile with no redundancy. One merely has to overcome gravity and windspeed ... the other gravitational forces and the atmosphere. Big differences.