Sure, he would have loved to beat Rafael Nadal at this year's French Open, but that was highly unlikely. Instead, that match just proves how good Federer is. It proves that even though he hasn't played particularly well this past year, and even though he hasn't played a close match against Nadal in a longtime at Roland Garros, he still has the ability to raise his game.
He is supposed to be on the back side of his career, and for a few hours, he gave the world's No. 1 in the world a heck of a match on Nadal's best surface. It gives Federer the proof that he still has the ability to compete at an intensely high level, and it gives him hope that he will be able to regain his Wimbledon title in a couple of weeks.
It sends a message to the rest of the player's that Federer is not going to just sit around for a couple of years playing at a non-championship level, and watch other player's win majors. He is still going out there and trying to compete for more majors.
It was good to see Federer out there playing quality tennis, because the last year and a half hasn't been right without him. The rivalry all of tennis loves is the one between Roger Federer and Rafael Nadal.