You are correct, high operating temperatures encourage additive and base oil failure. The widely used rule of thumb is that for every 18 degrees F increase in temperature, the life of the oil is cut in half. Still, it is common for high temperatures to be recommended in paper mill applications.
Reasons include better water-shedding ability, lower foaming tendency, better air release, improved particle settling rate, better drain back flows, and more rapid vaporization of water. However, most of the benefits from increased temperatures can be sufficiently achieved at, say, 140 degrees F.
At this lower temperature, viscosity will be higher and therefore you might want to revisit the viscosity grade selection. Lower viscosity oils, in general, are more resistant to oxidation and thermal failure. It is good advice to discuss a proposed temperature and/or viscosity change with your machine and oil suppliers.
