Yeah you're right, he's a good fighter, but a much more impressive mouth. That's his "USP", which is saying something in UFC.
He was really a perfect storm for the UFC from a marketing perspective. Confident, good talker by fighters' standards, from a pro-combat sport English-speaking country with little sporting success as of late and, crucially, had the skills to make all of that come into play.
The UFC is much better at branding than promoting, so they rely on guys like him appearing for them to shine a light on and hope they're good enough blow up, because they are frustratingly bad at selling most of their best fighters. They were hoping to replicate Conor's trajectory with Till, but he fell short. Adesanya's looking like the next guy they're trying to give that treatment to. I guess there's Covington as well, but he lacks pretty much all of Conor's appeal outside of being a solid fighter who's not afraid to talk shit(poorly).