Until the publishers can get a cut of the BAT ads revenue it is never going to become mainstream. People look for content (videos, photos, news etc) it just happens that the ads are on those pages because that is how the publishers make money from giving away content for free. If the publishers don't get a cut of the ad revenue from BAT they aren't going to have the BAT ads on their websites and therefore hardly anyone will see the BAT ads.
There are already platforms where you can get paid for just viewing ads and completing surveys etc and only a very small percent of people use these services as they are annoying when all your doing is viewing adverts.