Wasn’t Fatu using the nickname before the E? He shoulda snatched up the trademark during the time he was on the indies.
Thinking about this and you do have a valid point. What I will say is that it doesn't seem like these contracts the wrestlers have give them any leeway as far as going beyond them goes, especially in WWE. Like I doubt that even given the fact they may own the rights to their name our nickname, that they can just go out & make money on merch without the WWE approval or even them getting a cut of the proceeds. Granted the wrestler is the one who was given the name by birth and is doing all the work. But because the WWE owns them thru contract, they likely want control over things like that.
I know even in the nfl they had an issue cuz I believe it was Marvin Harrison Jr that was refusing to sign his NFLPA deal where they would be able to use his name and likeness to sell merch and games like Madden. Not sure if he has signed since then. But these companies and leagues do this so they can profit off of the athletes.
Of course the wrestlers likely get a cut of the sales from places like wwe shop but it depends on the contract they have. I'm sure not everyone is getting the same amount percentage. Also gotta consider the discrepancies between superstars far as merch goes. Someone like Cody could have 10 shirts and Priest could have like 3 so obviously one has a higher chance of making more money than the other.
It's a tricky subject cuz without the company you likely not making as much money off merch, but you still want to own the rights to your name if the opportunity to make money in outside ventures presents itself.