Why do our senses evoke different subjective experiences
Don't know the answer (I think no one does), but you should have a look at this paper: A sensorimotor account of vision and visual consciousness. O'Regan JK, Noë A., BBS 2001 PUBMED

In short the proposed answer is that modalities are subject to different sensory-motor contingencies. For example, when you move forward the visual input undergoes very structured changes, but auditory input undergoes a different set of changes. So what makes seeing feel different than hearing is that the relationships between motor output and sensory input are different.

You might also be interested in sensory substitution experiments. The brain is to some extend able to acquire new 'senses', when specifically structured information is provided to an existing sense. For example, it appears to be possible to 'see' (whatever this means in this context) when brightness information is transduced to touch or electrical stimulation of the tongue Wikipedia