Your question was what is the PERFECT temperature and in my opinion, and from what I read, 65F is not perfect. The perfect temperature is more like 55-60F with the cooler end being preferable. Like everything else, our decisions must be made in the real world and compromises are understood.
In my refrigerated 268 bottle wine cabinet, I keep my wine at 58F but that, ideally, may be a few degrees warmer than ideal.
So what is the difference between 58F and 65F? (yes, I know -- 7 degrees!) Well it may be more theoretical than realistic for the wines we are subjecting to that temperature. As you get closer to the ideal temperature, your wine will take longer to mature and the slower, cooler, longer conditions are more likely to facilitate the ideal maximum quality of any given wine as it matures. In the real world, that may or may not translate to actual differences, depending upon the quality and length of life of the wine you are aging.
If you drink all your wines in 12 months, your additional money paid to cool to 58F may be wasted. If you have wines capable of aging over 2-4 years, though, your 58F may make a difference. (but it may be small)
So the question is, how good are the wines you are aging? Since we don't always know the answer to that, are you willing to pay the extra money for energy to cool them when perhaps only a small percentage of your wines will actually be positively affected?
NS