The question should be what drives the story itself. If a Story drives the film then it's Art - sponsored by a brand and that's fine (even if the brand manages to get mentioned in the film). As someone said most art is paid for the rich and wealthy and now brands. Status quo.

However if the Story is driven by a Brands need to communicate/sell - soon the story becomes just advertising, the plots become weaker, the Art not really "Art" and we have advertising disguised as Art.

The problem is "We (consumers) know when we're being sold to, we always know". http://blog.brandkit.io/blog/people-know-when-they-are-being-sold-to