Then you're limiting every shuttle flight to one that is on the same orbital plane as the ISS...
This ain't a vehicle that you can fix with a Hefty Bag and some duct tape.
And I'm sure if enough scientist, and engineers put their brains to work, they could come up with a way to temporarily repair tile damage in space.
And if a shuttle is "too heavy" to reach space station, it should be mothballed and maybe put in a space museum.
Please read up on orbital mechanics before making such assertions. It is a question of orbital and vehicle parameters (inclination, plane, altitude, and available fuel) that determines this.
Specific missions make it impossible for the Shuttle to reach the space station. Among other things, if you want to use the Shuttle to fix a satellite not in the orbital plane of the Space Station, then you're going to have to accept not being able to reach the Space Station in an emergency.