The present system is set up the way it is for a reason. I recently flew r/t to London for $398 and due to various bonuses and promotions, I received 27,000+ miles. Forgive me for being a stooge, but I think it would rather unreasonable for me to expect a free seat to anywhere in North America at any time I wanted on the basis of those 27,000 miles. (Geeze, I can already do that trip three times and be elite, too.) I have no doubt that I will receive substantial value for those miles, btw. I just happen to also realize that it will involve using a little flexibility and know-how.
It is my belief that Flyertalk's population includes a lot of people like me. We learn the system and -- let's face it -- we exploit it. Airlines can put together very attractive programs that appeal to large masses of people because they know that there aren't all that many people with the time, flexibility and deep-seated desire to do what we do as an avocation. (Having a few of us out there is probably even a good thing; sort of like Publishers Clearing House needing to have a few winners.)
If you spend a lot of time on Flyertalk, it might be easy to believe that there is quite a large group of people who are doing what we do, but I'm sure it is rather small percentage in the broad scheme of things. (Just spend a little time explaining your antics in a group of normal adults and judge for yourself the percentage who think there is something wrong with you. There is a reason that many of us don't talk much about this stuff around the office.) And as attractive as a simple system might seem, there is an even more attractive "gaming" aspect to the present, convoluted system of fares and rewards that makes the whole thing rather compelling. So the heck with simplified fare schedules and straightforward "using miles like cash" anytime you want.