Its more to do with how expensive the land is, construction costs, the amount of units, and how can the developer make a profit based on all of this. Doesn't necessarily have to be tall. Its really a relationship that accounts for soft + hard costs, and the less units you have, the pricier its going to be to make up for those costs plus the head room for profit.
220 South Street is much shorter than 432 Park, yet it will boast a penthouse that's 2.5x the price of the most expensive unit at 432 Park. Its also in an area thats far more pricer than the lot that 432 sits on and has costs that are much similar in terms of hard costs.
I don't think 80 South will command the prices that 220 CPS is asking but its in the ultra luxury division. There is a slow down, but its not something that is approaching 0. There is still demand, but its not as bullish as it was 2 years go. But its still there and thus, towers like this and 80 South and 9 Dekalb will rise.