I'd call it hedonism if a couple wants to be able to go out on a date on a whim, easily take a vacation, watch adult-appropriate movies on a big TV in the living room, maintain good sleep/health habits, keep a flexible schedule unconstrained by school pickups/staying home with a sick kid, etc.
These are all real examples of why people I know delayed having kids, curtailed the number they had, or never had them altogether.
The degeneracy of these millennials who want to maintain healthy sleep habits...
It's unclear what you're saying. Obviously it's not hedonistic to "want" those things, as you say. You might use the term if they try to have their cake and eat it too, irresponsibly.
Hedonism has negative connotations, colloquially (and colloquially is how we are speaking).