FWIW, my $5 Beefy Tees from Hanes feel denser and more stout than my loopwheeled shirts. It's just that my loopwheeled shirts have a more interesting texture.
IMO, most of the appeal is the construction process -- knowing that your shirt was made a little differently. I like tubular knit tees, but I still mostly wear Hanes. There's something really nice about wearing a brand new white t-shirt, and it's a lot easier to go through a stack of new t-shirts every summer when they only cost $5 a piece, rather than tubular tees that cost $50-125.