First of all, he was holding back at the beginning of his career and wasn't very "controversial". Second of all, it's pretty normal not to be famous when you're low in rankings or not ranked at all. But the point is, once you get famous and people recognise you - you can't just switch it off.
I used to know Strickland only as a top 10 Middleweight fighter. I honestly think there is nothing special about this guy. He didn't have anything that would make him a star. He doesn't have a good match report and has lost to several unknown fighters. That's all I used to know about Strickland. But after his fight with Adesanya people already know Strickland and like you said, we can't turn that off. If Strickland can play his role well and have some controversy I think he will still be known and will be his selling point as a UFC fighter.
But I don't think we can equate Strickland with Nate Diaz. Even though Nate has a bad report card and as you said he hasn't won anything, Nate's persona as a Gangster is something special that only the Diaz brothers have. Nate is the image of an old fighter with a fighting style like street fighting. He went just to fight. And that's what makes it interesting to watch. Moreover, he is the younger brother of Nick Diaz, one of the most famous UFC fighters in history.