I think people sometimes overestimate what proving something means. For example the 4 color problem was a computer assisted proof from a long time ago. I doubt that many people actually read the proof even though leafing through the book is kind of fun if you can find a copy. Another example is the Kepler conjecture on sphere packing. The peer reviewers said they couldn't vouche for its correctness. While reviewers are volunteers with busy schedules, a lack of interest surely was part of the issue. This motivated Hales to formaly check his own proof (Gonthier formalized the four color problem earlier). But you can be sure that no one had been waiting for the Kepler conjecture to be proved in order to pack their spheres. Otoh, at the opposite extreme, the proof of FLT greatly advanced the field because the modularity theorem behind Wiles' proof is at the heart of a great section of math theory.