I would just be thrilled with a happy medium. They are either freezing cold (in which case even a sweater doesn't even help...and those stupid blankets they provide are barely more than a tiny sheet), or sweltering.

Yes, I agree, 59 degrees is probably the ideal temperature for sleeping, but that's with blankets. And up here in the NE, they still have the A/C cranked down to 60 when it's only 72 degrees outside! I am constantly asking the FAs to turn down the A/C...