Great topic. The reason it comes up frequently is because it matters.
I have lived both sides of the question, so I will share my experience. I was a 6-2, 159 lbs. HS and D1 stud. But my studliness stopped hard at the track. Girls were not digging it. 159 is very, very thin for my genetics, and does not look good at all. It was required for racing, but I had to diet to get there. Even at 80mpw, my body wanted to weigh more, but lighter was faster for me. (note, I am a 800-1500m man, not a 10ker) I had very, very little success with ladies in undergrad.
After D1 career was over, my running went to 25mpw tops, and I hit the weights hard 3-4x/week. My natural genetics were rewarded--I was working "with" my body, instead of being artificially underweight. I didn't do any special eating or supplements-I ate whatever I wanted. I packed on lean muscle like a boss. Over 18 months, I ramped up to 185, and it was all golden, rock-hard muscle.
I'm not going to be falsely modest--I looked utterly amazing. I had a physique like an underwear model. My "default" physique is not huge and burly and thick, but it is also not runner skinny. My default is that 175-195 mentioned by others.
The change with women was staggering. Nothing changed in my personality, finances, etc. but suddenly I could do no wrong with the ladies, especially at the beach/pool with no shirt on. My mid-twenties were tons of fun, and the ladies could not get enough. I absolutely disagree that it doesn't matter, confidence, blah blah blah. No way. Looking like a greek god opened up access to attractive women in a way I could scarcely believe.
Now 12 years later, I'm married with 1.5 kids, work crazy hours, and rarely work out. My default is still 175-195, but now the composition is a lot more fat, and I'm not blowing anyone's mind when shirtless.
The flip side? Nothing in life feels quite like being razor thin and efficiently running, and having the ability to float at high speed effortlessly. I can completely understand why "non-elites" might enjoy being thin--the freedom of movement it provides is hard to describe. When I was in my underwear model prime, going for runs just wasn't the same--it was a grind, not a thing of effortless grace and beauty.
I agree with others that no one gives a sh*t about the difference between 15min 5k and 18min 5ks, but if you love being light and fast, do your thing.
But socially and romantically, 18min and ripped is much nicer.