>I wonder if a lot of that has to do with how it's being "marketed" --- it might just be me, but whenever I see "modern" being used to describe something, it evokes the negative connotations of being trendy, fashionable, boring, vapid, fleeting, style-over-substance that's all too common with software today

For me, when I see people waxing poetically about the unix way and the old, crufty, POSIX userland, it's all about cargo cult, "that's how things have always been", minimum viable progress while keeping compatibility, and heritage-over-substance.