At warm fermentation temperatures, more esters and higher alcohols are produced than at colder temperatures, resulting in more fruity, floral flavors.
Yes, higher alcohols, otherwise known as fusel alcohols or or fusel oils. These are likely to be produced by higher temperatures, and other factors that promote rapid cell division and growth. The problem is these fusel alcohols are very harsh. They create a burning sensation like rot-gut whiskey in the back of the throat. They sometimes smell bad (nail polish anyone?), and the increased concentration of alcohols may actually mute the aroma detection of wines/meads when sniffed.
Higher fermentation temperatures may also lead to various phenolic compounds and vinyl phenols that can smell like Band-Aids and to more sulfur odors. Also worth noting, the rapid fermentation at higher temps may blow off more aromatics that get scrubbed out with the CO2, so even though producing more, more get lost. If that wasn't bad enough, though higher temp fermentations go faster, then tend not to go as far, and may leave you with unwanted residual sugar if not a stuck fermentation.
There is a belief by some wine/mead makers that a slower fermentation may be better. Certainly a debatable topic.
Can you make an award winning mead at 75F? Sure, but it will depend on your recipe, yeast, and other management.
If you are making a traditional mead using 71-B, it it known for producing large amounts of esters and will give you a nicely fruity and floral result. I would ferment as close to the bottom of the temperature range of the yeast as possible, as I think you'll get plenty of fruitiness with a smooth tasting result.
It is perhaps worth remembering that higher temperature fermentation are typically used with red wines to help maximize color extraction and tannins. They tend to wind up with less fruity aromas as a result. It would not surprise me if dark berry melomels would behave similarly with good results even at temperatures in the high 70s or low 80s and perhaps this summer a group brew can be organized to test it out.
Good luck with your batch!
Medsen, fuselier extraordinaire