Numbers, dude. Show your work. It's not that I don't believe you, but let's all get smarter at this together.
I also want to remind all of you that Roman isn't fighting for the title, because he lost that feud, so he's not the top guy. The Undertaker retiring was going to go last.
WWE's house show numbers have been dropping for the last 2 years. Coincidentally this coincides with Roman Reigns becoming a main eventer
http://indeedwrestling.blogspot.com/2016/10/whats-happening-with-wwe-house-show.html
http://www.wrestlingforum.com/general-wwe/2068586-wwe-house-show-attendance-down.html
All WWE Events in US & Canada (including TV & PPVs tapings - excludes WrestleMania)
Q1 Q2 Q3 Q4
2014 6400 6000 5100 5700
2015 6700 5400 5100 6300
2016 6100 5400
All WWE Events in US & Canada (house shows only)
Q1 Q2 Q3 Q4
2014 5200 4500 4300 5600
2015 5500 4300 4300 5700
2016 4400 4000 4000
Both links reference the Harrington Analysis of Wrestling Observer Newsletter Results numbers as well as WWE's on released data. Couple this with the declining television ratings and the lack of growth in younger demographics and there's literally zero evidence to support the notion that Roman Reigns in his current state is helping the product.