It appears to me that an out of context taken statement got turned, twisted and demonized. If you've been on the other end of the spectrum you'd understand how aesthetics matter.
The misconception comes from perpetuating that aesthetics don't matter at all. In my perception the original statement was aimed at the drawbacks of training solely for aesthetics and reverse engineering aesthetics to a training style.
There are some considerations: 1. If aesthetics is the reason some people start training, does it matter? Isn't it more important to get them trough the gate? Yours truly started physical exercise because I wanted to be more aesthetic. Although I took the calisthenics route compared to the modern bodybuilding "fitness" route. And eventually adjusted course. What I started for is not what has kept me in the game.
2. Some (not all) that scurried behind aesthetics don't matter use it as an excuse to hide behind. It is OK if you don't want to chase aesthetics nor do some of the long and short term work needed to acquire it. There are some outliers that genuinely don't care,which is well within their own right. Perhaps down the line (as we age or grow wiser) it could potentially matter less.
3. Looking good is feeling good, and visa versa. The biological manifestation of this with hormones and behavioral patterns should be obvious. If you're not sure about that: go to the other end of the spectrum for a while and see what does that you. At least you have more reference points to reason from. I have been on that side of the spectrum, it is definitely not preferable compared to the other side.