Though it’s obvious that she has supporters backstage, Asuka apparently cannot count Vince McMahon among them, according to Brad Shepherd in the Oh, You Didn’t Know podcast. Here’s what Shepherd said (h/t Ringside News transcription): 
“Certain people in WWE love Asuka. Now here’s the key: Vince doesn’t but everyone else does apparently. Hence her booking in NXT with the Goldberg streak and then winning the first Women’s Royal Rumble. Asuka, she doesn’t sell a dime in merchandise.”
There are perhaps reasons to explain why Asuka isn’t easily marketable to American audiences. Though she is a talented performer in the ring, she is not able to talk much during promos and fans may not connect with her because they don’t know much about her or her history before the WWE. Whatever the reason, she still earned the SmackDown Women’s Championship and can perhaps parlay that into gaining more of an audience, merchandise sales and perhaps win over Vince.