Not trying to be a smartass, and not advocating flying into hail or cb but the resale value of that 747 probably wasn't extremely high even before it was damaged. iI a decision to write it off is taken, it reflects repair cost > residual value, not "damage" alone.
And, in some cases like this, the repair will be done, even if it doesn't appear to make sense economically just to avoid a 'hull loss' which can drive up fleet insurance rates. Or, look bad for the airline 'Rainman' safety record e.g. QF1 at BKK.