I've lived in Hong Kong, which is a similar order of density, and which I loved; it was a feeling of being vibrantly alive that's hard to duplicate in a more spread-out environment. Also spent a decent amount of time in Mumbai and enjoyed that - though I might not have if I were one of its poorer residents. Would it be worse than being poor in a village? Not sure.

> It's quite clear that with population density, trash output also increases and is harder to manage.

You're saying that 10 people per km2 produce more trash each than 5 people per km2? What's the mechanism at work there? I'd think denser cities means smaller houses and therefore less room for spurious stuff.