TAs on any cruise line are atypical. Always attracting a rather "ancient" crowd. We're the ones who have the time to be away that long
I do think for some time Celeb has tried to target the upscale passenger, though I don't think young would necessarily be included in that. On their Caribbean sailings they still try to draw plenty of families, because that is kind of the life blood of Caribbean sailings on large ships.
As far as the offerings on luxury lines VS premium... there is a noticeable upgrade in passenger space ratios, as well as level of service on the lux lines that carries value too, though not easily monatized.
At dinner, there's no awkward moments about whether you should offer to share wine you purchased, or if you should except your tablemates to reciprocate next time. It's included, so everyone orders what they want.
Part of the lux package is the elimination of most awkward moments regarding alot of little interactions taking place.
I have been quite smitten by my luxury cruise experiences, but then, I may have felt different if I was footing the bill.