User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-23847729-20141105105810/@comment-16281343-20141109213257

Issei's promotion is imminent. Everyone knows that and the whole underworld acknowledeges his achievements. He is the hero of the Underworld, not Rias.

Even if you want to have Issei have his promotion now, what's he gonna do with it? Play chess with someone using the EPs he's gonna get? With all the things happening, there's nothing he can do. He and Rias doesn't even have time for themselves. The current timeline isn't the same with the earlier Volumes. There's not much hang time between Volumes, events happen in just a span of days, unlike in the past.

~Of course there will be praise that will go to Rias' way since she is Issei's master but that doesn't overshadow Issei's spotlight.