I don't have super-strong opinions on network size necessarily, but assuming that what you say is true, and that this isn't a generational/cultural preference that might evolve over time, it still doesn't strike me as a particularly powerful critique?

The argument here isn't that small towns are preferable, the argument is that they are better, and that they lead to overall healthier social groups.

I don't want to exercise. I want to eat sugar, I don't want eat whole foods. I might as well say, "when are these doctors going to realize that eating healthy and exercising isn't what people actually want to do?"

Whether or not smaller communities are healthier can be debated, but whether or not people want to have smaller social networks is kind of orthogonal to that debate. You can advocate for something that is healthier and that will make your life better and that will overall make you happier if you put in the effort to pursue it, while acknowledging that people are not generally biologically inclined to want to do that thing. In fact, most healthy things that we advocate for in life are not things that we instinctively want to do and are things that require conscious effort and conscious denial of behaviors that we might prefer -- that is in many ways the norm, not an exception.