Not observing any gravitational waves wouldn't prove that gravitational waves didn't exist, so there wouldn't be nearly as much fuss and news articles written.

Not observing any gravitational waves wouldn't prove that gravitational waves didn't exist, so there wouldn't be nearly as much fuss and news articles written. Imagine the press release: "Jury still out on existence of gravitational waves: LIGO not sensitive enough/ Is LIGO a gazillion dollar waste?." So while if someone were able to PROVE that gravitational waves didn't exist that would be pretty spectacular because it would upend decades of scientific research and cause us to rethink relativity. But this is still pretty spectacular in it's own right. The predictions that physicists make are made by examining mathematical models that are only partially vetted. Some parts of the models remain theoretical because we don't have instruments sensitive enough to measure their predictions (we are talking about energies on a ridiculous tiny scale here). Finally we have invested millions on an instrument that is sensitive enough and it confirms (to the best of its ability) that we were on the right track. This is a great relief to the scientists that they don't have to go back to the drawing board and rethink all their models, plus it is a great victory for predictions made before the age of computers.