I think there's some muddling up here of what parents buy for young children, and what older children might choose to wear.
My DC might have chose to wear sparkly/tracksuity clothes when they were very small, but they never had that choice, as those things weren't available to them. What was available to them was t shirts, shorts, cords, chinos, shirts, jumpers etc. Normal clothes, really. DD had lovely dresses and wool coats (nothing pink). She used to wear a Snow White dress over her 'proper' clothes, though. I dare say she'd have been in Princess-emblazoned tracksuits if they had been on offer.
On the whole, teenagers either rebel completely and wear all the stuff that their parents hate, or they have internalised their parents' views of suitable attire, and dress accordingly. If any of mine (all late teens) suddenly started wearing joggers and football shirts, I'd think they were doing it to rile me (which they probably would be, so I wouldn't comment on it). DP also dresses properly, as do I. Unless I'm gardening or decorating or dog-walking or some such, obviously. If DP started wearing joggers, I'd think it was fair grounds to leave him.