#2. Lack of quality heel opponents for Seth Rollins
A Champion is only as strong as the men that line up to face him in battle. A classic case is Finn Balor, who had been the Intercontinental Champion for a while, but hardly had any title defenses until earlier tonight. The IIconics also fall into this category.
While Seth Rollins has always been a featured performer since WrestleMania, the feuds that he's been booked in have failed to deliver. There was a babyface vs. babyface feud with AJ Styles that resulted in a good match but did not exactly set the world on fire, in my opinion. The Baron Corbin-Lacey Evans program with Becky Lynch just sucked out all of the excitement associated with Rollins.
Whom would Rollins have faced next for the title? A program against someone like Elias or Drew McIntyre wouldn't exactly be as big as one with Lesnar.