Gotta remember, technology went from space age, to stone age, in a few short hours. Space exploration can only be undertaken with a HUGE industrial capacity, and infrastructure to support it. For a good long time, after the war, day to day survival was far more important than ANYTHING else. Only the strongest survive.
Granted, we have come a VERY long way in the last 100 years. However, that was a (relatively) healthy, developing, society. Now, remove ALL the artificial supports for that society, and it does indeed collapse. Rebuilding is going to be a slow, and tedious process, and the roadblocks involved are much more difficult to overcome.