Because designing the mobile version of a Wix website is my least favorite part of my job, I would love to see a new feature called ‘make your website with one click responsive for all devices’. But I guess that’s not possible? 
In that case; every new feature that helps designing a mobile website with less work would be great.
And I think it is also in the interest of Wix, because there are so many Wix users who forget to make their website mobile-friendly, or do not know about this tool/feature/must-do or simply do not understand why you should actually make two versions of a website.