Does art in the real world always have to serve a purpose? Does it in the fantasy/sci-fi world?
Yet, it usually does. As already discussed, these giant towers are air scrubbers. They could have made them into utilitarian, ugly towers . . . but instead decided to make them imposing giant, super-cool statues. Also, they are a part of the illusion the RI projects, the illusion of control, of power, of stability and safety.
It's a very deliberate and purposeful part of the world-building for this show.