well i'm not an expert of Quran. though we don't know the exact reason for those kind of "not clear enough" statements, i think they are meant to be this way. for example you say in your post:
"For example it would be so easy for millions of people considering many are uneducated to give simple a command O you believers Pray in the morning before sun then at noon and after noon beofore sun set then after sun set and before you go to sleep when stars are brightly visible. Then there will be no mixed thought or suspicions about the exact order of pray times."
As soon as i've read this, i thought about polar circles. there are people who can't see the sun for a quite long time in a year, or the opposite, they are under darkness for such a long time. if prayer times were mentioned like you said, they would be useless for those people up there. but i personally think those prayer times indicate specific portions of a day, so that everyone can understand them. for example isha prayer is for "the last part" of the day, before we go to sleep to rest, it's a night prayer (or "the last part of the day" prayer for people who don't experience dark nights), noon prayer is for the middle part of the day when we are all busy working, studying, in the middle of our daily actions and that can also be determined by the people who don't see the sun in winter. asr prayer is for the time we are now prepared for the "evening" part, we are close to the "sunset", we are getting ready to go home etc... and so on....
So all the people on Earth could determine these portions of the day in such a manner that is common and widely accepted. But again it's just my personel opinion. May Allah guide us to the right path if we are wrong.
Sorry for my English by the way, I apologize if i couldn't explain my thoughts clear enough.