Why do we see?

Why - because we have eyes, and their connected to the brain, of course.
Is it that simple? Not really. Our eyes are connected (not directly though) to the visual cortex. From that point, increasingly complex representations of the raw input are transformed into representations of scenes, objects, faces, etc.

But we do not only acknowledge the locations of all of these various object types. It's not as if we have some vague notion of the presence of faces, objects, hands, and everything else in the scene. We actually see an image, which means that we have access to the "raw data" of our sensors.
Of course, this is an extremely simplistic view of things, since the actual region of an image perceived with high acuity is actually deceptively small, and our brain works it out to make this less apparent. Everything around the very center of the field of view becomes increasingly blurry, allowing only motion and rough color and shape to be captured by our attention (and faces and hands, but that's a special issues).  There are many other details about that which I'll not go into here - So forgive me for using the term "raw data" or "raw image" very loosely - for now assume it's just a given image.

How can this be true? this must mean that there is also some bypassing mechanism, allowing the "raw" data to be transmitted directly to an area in the brain where it can be examined in our conscious mind. 

It is interesting to try to explain, in evolutionary terms, the existence of this feature, which seems non-trivial to implement. Why did vision evolve in this way? What are the advantages of such a dual representation? How does vision work for animal for which, I assume, there is not clear-cut notion of
consciousness, e.g., ants? Perhaps in such life-forms, they have access to the visual system's conclusions but not to the "raw image"...

Arguably, in humans (and other primates), there is an interplay between our perception of high-level concepts such as objects and scenes and our direct perception of the image. But it is almost certain that it will be a long time before we understand how this happens, how conflicts between the two are resolved, etc. As always, we can probably learn more from pathological cases, where the image is available to the conscious mind without understanding, and more curiously, maybe the understanding is available without access to the image.

This observation about the dual access to sensory inputs and their interpretation is true for most if not all senses, e.g., hearing, touch, taste, smell. It is also a crucial factor in the development of pattern recognition. Imagine a world where we only had access to our brain's interpenetration of the sensory data and not the data itself. Then everything would be taken for granted, e.g, we would naturally think that there is nothing more to the world than the things we perceive.
In fact, this is true for any possible setting: it is natural for any being to assume nothing else exists except what its own experience teaches it.

If anyone has physiological / evolutionary explanations for this - I would love to hear (see) them.