The only point of changing the build from smoothly blended to layered is to create taste profiles of the layers.

Hot caramel macchiato. Aroma: caramel sauce. Practically irresistible. Acidity: relatively, and mediated, high acidity, and then low. It cleanses the palate, and leaves nothing but milk and sugar. Body: heavy, and then neutral. 'Yes, this tastes good' to 'yes, this is what is in my mouth.' Flavor: complex super-sweet to bitter, and then milk and sugar.

Iced caramel macchiato. Aroma: replace this with the visual appeal. Acidity: what is most sought after is left as something to be anticipated. That freshness is the last step, and it's enjoyed as the coldest part of the drink. Body: if the part with less ice, the bottom, was heavy, it would be more likely to repulse a person already feeling the heat. Iced, bitter, with that sweet note of caramel, hanging on the tongue, that's the stuff. And flavor, maybe less important in a cold drink, except that it's all familiar. Hi vanilla!

And if it's made hot and mixes together, maybe it wasn't made right. Good foam, careful pouring, it should layer nicely. Letting a three second aeration set for a bit makes something of a difference.

This is mostly conjecture. 'Bout to try in a class cup, though.