This lake can come up real quick, and when it does they can't just open the gates and blow the Osage out of its banks.
We also have a buttload of shoreline property owners that think their property value decreases if there is milfoil around their docks. The drawdown and frosting of the shoreline out to 4-5' during the winter keeps the milfoil and hydrilla from taking hold. Personally I'd LOVE to have the milfoil return, but....
There's also considerable seawall work that can't be done during normal pool, and construction crews that need work during the winter, so the drawdown allows that to happen.
Kind of a Win, win, win.
Another cool thing that comes from the winter drawdown that a bunch of fishermen don't realize is that during the first few warming trends of Spring the crawdads that are burrowed under the high & dry seawalls wake up and crawl back down to the waters edge. This "hatch" is what puts the bass on that killer jig and Wiggle Wart bite that everyone looks forward to.