The problem is that a frequent-flier mile does not have a well-defined legal structure or definition wrapped around it.

The organizations that would demand that transparency - the SEC, IRS, etc. - don't really know what to make of FF miles. Therefore, the programs don't have to operate the same way your mutual fund has to operate. They can print currency all day long and sell it to partners at 2 cents a mile, and then carry it on the books as some miniscule amount. They can change the programs at any time to effectively make the miles worth more or (in most cases) less. They can decide when you can redeem your miles and when you can't. It's all perfectly legal because miles are not a currency, a commodity, a futures contract, a coupon, a guaranteed discount, or anything else with a solid legal definition.

This vagueness benefits the airlines greatly, but it benefits us too in that the IRS generally ignores our mileage "earnings".

As for your scenario of 5 award seats on a peak flights vs. 35 on a non-peak flight, I've always assumed that this is how the programs have worked forever. I don't think it's a new idea: I guess it doesn't bother me much because that was my expectation when I started accruing miles. My FF history has mostly been with AA and UA, and with those two I have usually been able to redeem my miles when I've wanted to, provided that I have a little flexibility.