While it's true that overall living conditions have improved, with more access to amenities like plumbing and clean water, this doesn't mean inequality has lost its relevance. Inequality still has a profound impact on mental health, social cohesion, and overall well-being.
Many people in developed countries live in makeshift housing without basic necessities like electricity, plumbing, and clean water. This indicates that not everyone benefits equally from societal advancements, and calling these amenities "privileges" overlooks their fundamental importance.
Furthermore, while obesity is indeed a prevalent issue among the poor today, it often results from limited access to healthy food options, which is another manifestation of inequality. You also mentioned that inequality contributes to obesity, so dismissing it as a scapegoat contradicts this observation.
The poor of the past might view our access to "stuff" as utopian, but they wouldn't likely see the lives of today's poor in the same light. Improved material conditions don't necessarily translate to improved quality of life, especially when disparities in wealth and opportunity persist. Quality of life involves more than just material wealth; it encompasses family, community, purpose, and other non-material aspects. Inequality affects all these dimensions, making it a crucial issue to address.
In modern times, obesity is one of the biggest health issues among the poor. The poor of times past would think we're living in a utopia. And in terms of "stuff" we probably are, but it doesn't feel like a utopia because it obviously isn't. Current times are probably the best evidence imaginable that all of the things we relatively ignore in terms of quality of life (family, nature, philosophy/purpose, and so on) are, at the minimum, no less important than the things we obsess over like income, education, and sexuality.