I don't know why google did it that way, but I suspect this was acompromise they decided upon to make app development a LOT easier.
after all, how many of us write code that checks the return value of
close()?
google was likely desperate for apps at the beginning. their app store
had nothing in it. even now I'm not sure it was the wrong decision to
make... apps asking for too many permissions and then abusing them is
the real problem. I don't think it's the permissions model itself.