If you check the copyright dates of those books, they where written some time ago. Not many years ago, the lower temps where still recommeneded though.
SW holds very little
O2 in the first place and lower temps are employed to allow for more
O2 saturation 77.4° being optimum. Considering the advacements in equipment and their efficiencies as well as our increased knowledge in husbandry, these temps are no longer a must and we can offer the animals we keep much more natural environments. As
WarOrks15 pointed out having the proper water movement as well as open surface area for the tank and good air flow in the tank room, good
O2 levels are more than possible. If you can keep a stable
ph level in the 8.1-8.3 range (testing time dependant) you will not have a poor
O2 level.
Higher temps do not actually increase waste production but rather increase the rate in which wastes are broken down. As far as aggression related to increased temps, I have never witnessed that myself. I actually had more problems with smaller tanks that could not be outfitted with a heater. Tanks large enough to utilize a heater for higher stable temps where
IME much more stable and less prone to problems. I did however find that with the higher temps that salinity must be much more accurate though. If too much higher above 35
ppt, nuisance algaes where much more prone to being a concern. Chemistry will also come into play but that's a different topic.
Cheers
Steve