Thought this was pretty interesting. Someone on r/SquaredCircle made a graph of WWE/World/Universal title defenses and the possible correlation to ratings for RAW.
Pretty much the more title defenses happened on RAW in a given year, the better the yearly ratings were while Triple H's Reign of Terror started the current trend of having a lot less title defenses on RAW. Also 2011/2012 being where RAW's trend downward was too much for title defenses to be a factor anymore.
https://www.reddit.com/r/SquaredCirc..._championship/