What I mean is that fighters need to add charisma too, otherwise they'll earn much less. I'm sure his contract should be the same as Alex's, simply because of the value Alex brings to the fight.
So, when he has charisma, attracts fans, and is famous, he can earn much more; that's a fact. And he can also negotiate with the UFC itself. If he's happy with earning less, that's fine, it's a choice. But in the long run, that's not good, when he could be earning much more.
I'm not saying that you're wrong in what you said, I just don't necessarily think that fighters should be pressured to do any public relations stunts just to sell more tickets/PPV. Yes, it is in their own financial interest, but let's not expect all of them to engage in acting or some other fakery when they're pretending something they are not. As fans, we should discourage that, as this is just dumbing down the sport and if we are to go that route, we will end up with some total WWE-style circus.
If someone is naturally not very charismatic, so be it, not everyone can. And the language barrier is also a factor. Fighters who don't speak English very well, or at all, would have a hard time making a show in the pre-fight conferences etc.