The problem has never been the rating. The switch from TV-14 to TV-PG happened in when...middle of 2008? It's not as if things were amazing in 2007 or years before. Based on several interviews with former writers, most of the time the WWE wasn't even writing TV-PG, but TV-G, so they knew they were following the guidelines.
It all comes down to the writing though. The entire period from when Vince Jr. took over in 1983 until the Attitude Era began was all basically TV-PG. Yet, the WWE made some things works (Including a gigantic boom). Things like Cena writing "Poopy" on JBL's limo wasn't a product of the TV-PG rating. It was a decision made by the creative. Things won't magically improve with a rating change.
Do you know what TV-14 really means? It merely means the ability to show middle fingers, have a few tame cuss words, show your women in degrading positions, ramp up the sex and increase the violence just a tad. How does any of that improve the quality of the show? I mean hell, at the height of the Attitude Era, channels like TSN in Canada and Skybox in the UK would edit the hell out of the shows to remove the TV-14 elements. So it's not as if you can't have a popular worldwide company without TV-14.