I think the idea is to try and build Carmella up as at least a moderately credible threat. Hence her beating Charlotte and Asuka. If she can beat those two, she can in theory beat anyone.
The problem is that Asuka isn't the underdog... no female on the Smackdown roster right now is likely the favorate against any of the heels. That's precisely why Carmella needs to be built up as a threat.
Plus, if you look at what happened last night Asuka really didn't look that bad. Ellsworth essentialy ran from Asuka, and Carmella cheap shotted her from behind then withdrew while Asuka was recovering. The fact that Ellsworth ran rather than face her in the ring (and this was a guy who wrestled AJ Styles) sells her dominance just as much as her beating Ellsworth IMO. The only reason she didn't win the match again was because he ran... a option he won't have next week.