Cinema has always walked a tightrope between art and commerce. On the one hand, you'd hope that any filmmaker worth their salt would take some degree of pride in their artistic vision, and would seek to make their mark creatively; on the other, movie-making is an extensive and costly undertaking, and there's always a need to make that money back with interest for all that effort to be worthwhile.
Every so often, though, directors with particular ambition and nerve decide to throw caution to the wind and go all-out. Never mind whether it'll win over audiences or critics; never mind whether it'll make its money back or not.
We don't see filmmakers throwing caution to the wind in this manner all too often, and when they do the results aren't always everything we'd like. Donnie Darko writer-director Richard Kelly took such an approach on his second film Southland Tales, and that pretty much killed his career on the spot.
However, on occasion directors really need to say to hell with everything and everyone, and make that film that only they can make - and when they get it right, the results leave us all richer for it.