Her MMA credibility is greater than say, a Sonya Deville's.
That being said, they're pushing her because she's a legitimately great women's wrestler. Both from the standpoint of her working style, and her ability to be a good base for other people's styles. She has the little things about heel work down that project clearly to people in the nosebleeds. She's not supposed to be attractive for who she is and how she works.
She's also the one from Ronda's little troupe that trained in wrestling first, has trained the longest, and actually went and put in work in other countries like a straight indy type, before she got to NXT. She had a title match against Io in Stardom.
Shayna's likely getting that call-up anyways. And... what more do you want from NXT for Bianca? She's the #1 contender and had 8 eliminations in this rumble... and that's from someone who most of their casual audience has never seen much from. The same way you feel about Shayna, they feel about BB.
Also... how do you know anything about Bianca and not know who the fukk Shayna Bazsler is?

That would be like me going 'man, I like this Scorpio Sky cat, but... who the fukk is Christopher Daniels and why is he on my TV?'
(As an aside: 15W/11L isn't a worldbeater in MMA, but it's impressive considering 13 of her 15 wins were by submission. Means they know what you're gonna do, and most of them weren't able to stop it anyway.)