Seth Rollins is the current WWE World Heavyweight Champion, he won the champion by defeating AJ Styles at WWE Night Of Champions. Some fans consider World Heavyweight title as secondary title. It was expected that WWE could ask Roman Reigns to relinquish one of his title, so that both brands could have their own title.
WWE had some other plans, they wanted to continue with Roman holding both major titles. On the other hand they did not want to make RAW unhappy, so they introduced a new World Heavyweight Title, which was won by Seth Rollins.
Seth Rollins recently was in Mark Andrews: My Love Letter to Wrestling podcast, where he talked about the World Heavyweight Title
“I think just kind of calling it the work rate title is a little bit underselling it. At the end of the day, the title exists because our roster is so chock full of talent, right? There’s just too much to have one champion that’s not around very much. And so I think the fact that we have so many worthy contenders, people that could hold this championship, I think that is the reason the title exists.
“If we had a weak roster, and things weren’t good, and stuff wasn’t hot, it would be a different story. It might be fine just to have one champion who wasn’t around and didn’t want to make live events, but that’s just not the case. You know, we’re selling out left and right. We’re hot from here to Jeddah, Saudi Arabia, Paris, France, Mexico City; it doesn’t matter.
“We’re just selling out left and right, and we need to have a World Heavyweight Champion on the men’s side to represent that level of competition, and so I think we’re going to put in the work to build this title to be as big as any championship in wrestling, and we’re not naive to think that we don’t need to put in that work. We know that it needs to happen. But like I said, you’ve got the roster and the guys and the crew who are willing to put in the time to make it feel as big as it is.”(H/T: WrestleZone)