Because koran is put forth as unchanged word of god, it is impossible to find any excuse to reinterpret it.
Some of the things you say might very well be true and I certainly find some of it interesting, but you seem to be leaning a bit heavily on this pillar (semi-pun intended). From the simple fact that followers of Sunni and Shia (not to mention all of the other smaller factions) are abundant there obviously is room for interpretation. Why would a more modern one not be possible?
For that matter, though I'm by no means an expert, I seem to remember that the OT is supposedly the word of god as well. I guess you could argue that jewish oral traditions might have miss-remembered and made it not the word of god anymore and that by translating it the meaning has changed, but I think a lot of people would disagree. I see plenty of interpretation regarding this work going on. Including, but not limited, to the muslim, jewish and christian readings.
Either or, the point is, it is ALWAYS possible to interpret things in a different way. I bet even the five word Hallmark birthday cards can be interpreted in five-factorial ways, at the very least. It's a human trait.
To do two things at once is to do neither. -- Publilius Syrus