The term "decadence" appears to be linked to decline of all things, including morals. It's loaded with meaning. Consider wikipedia's treatment of the concept
In literature, the Decadent movement—late nineteenth century fin de siècle writers who were associated with Symbolism or the Aesthetic movement—was first given its name by hostile critics. Later it was triumphantly adopted by some of the writers themselves. The Decadents praised artifice over nature and sophistication over simplicity, defying contemporary discourses of decline by embracing subjects and styles that their critics considered morbid and over-refined. Some of these writers were influenced by the tradition of the Gothic novel and by the poetry and fiction of Edgar Allan Poe.
Use of the term decadent frequently implies moral censure that such declines are objectively observable and that they inevitably precede the destruction of the society in question; for this reason, modern historians use the term with caution. The word originated in Medieval Latin (dēcadentia), appeared in 16th-century French, and entered English soon afterwards. It bore the neutral meaning of decay, decrease, or decline until the late 19th century, when the influence of new theories of social degeneration contributed to its modern meaning.
Which is, I suppose, an interesting intellectual cul-de-sac to explore, should one have the time (I don't), But for me, denunciations of decadence have the moldy whiff of conservatism, fretting about how far we've fallen from the good old days, when women knew their place, gays stayed in the closet, or better yet, in prison, and people could speak of moral hygiene without provoking peels of derisive laughter.