When Paul Delaroche (a mainstream painter of ultra-realist historical works) said: "From today, painting is dead" (1839), what he meant was that photography - Daguerrotypes, at the time - had taken over as the principal artistic method of representing reality. Painting of course didn't die; it rapidly developed a very successful non-realist, non-representational aesthetic.
Few people would claim that photography is totally realist (the minority school of ultra-realists in the 1970s being an exception which I think proves the rule); anyone who does make that claim misunderstands photography and perception. However, it does have a particular claim to being realistic (representational) on two grounds. First, the distortions and misrepresentations it routinely presents are distortions and misrepresentations of something that is really there; and these are accepted as by-products of the process. They are not, except for adventures of technique, special features created by the artist. Second, (with some special exceptions) photographs are made of some thing, not derived from the artist's imagination: tricks can certainly be played, but the real world and what can be photographed act as controls or limits on pictoriality.
This is the aesthetic legacy of the f/64 Group in particular, and of course we don't have to slavishly follow that unless we want to. However, I would argue that something very like it is at the heart of all analogue (= film and plate) photography; on the other hand I think we are seeing (in popular culture, at least) a recession from representation in favour of an aesthetic which sees the "digital photograph" as merely raw material for the creation of a desired re-presentation, much more like painting in its theoretical approach (whether acknowledged or not).
We have a choice. We may not all be aware of having the choice, but (in my opinion ) it's there to make. And that, for me, is the importance of film photography.