United State Championship Match: Samoa Joe (c) vs. R-Truth
They added Rey Mysterio vs. Andrade to Fastlane after SmackDown, so they could have easily given Samoa Joe a showcase match with his newly won US Title.
R-Truth has been entertaining in his role as comedic face champion but the shelf life on his reign was going to be short regardless of his ability.
Since they triggered the change on the SmackDown before the PPV, it would have been a slam dunk match for the PPV.
The US Title needs to be featured more and the matches that R-Truth had with the title were actually pretty good. But the whole 'no automatic rematches' is only true when WWE wants it to be.
It actually was a pretty easy way for them to book matches rather than have the challenger re-earn a title shot a la AJ Styles and Becky Lynch at the Royal Rumble.
Joe's ability as a workhorse will continue the quality of the matches, but if it goes back to showing up once a month on SmackDown, it will not have changed anything with the title's booking.