I think there's some logic in supporting another HST repair flight:
The HST was the most successful Shuttle related program and it could produce better and better pictures years after the shuttle will have said "Adieu", if there's another mission to it.
OTOH, what enthusiasm would there be in going on with the ISS construction if you know that as soon as it will be "completed", it will loose its main partner and all its various objectives?
When one builds something, there's far more than completion to envisage, there are all those years of exploitation, discoveries, dramas, etc...But that would be cut short.

Raoul