#3 Never had a proper WrestleMania moment
A successful intercontinental title defense against Baron Corbin doesn't count as a WrestleMania moment. Rollins pulling off the 'heist of the century' at WrestleMania 31; now that's a moment!
Roman Reigns winning the WWE World Championship against Triple H at WrestleMania 32; as much as you may despise it, was a significant occasion, at least for the Big Dog.
Compare that to Ambrose's showing at the grandest spectacle of them all and it's just pale in comparison. Don't even get me started about the 'No Holds Barred Street Fight' against Brock Lesnar at WrestleMania 32. Ambrose can be a little lackadaisical in the ring at times and his matches may not always be classics, but that can also be attributed to the curtailed creative freedom.
WWE has always been skeptical about going the extra mile with Ambrose and his WrestleMania history is proof of that.