Yesterday I did some imaging outside with only two (50mm f1.8 and 200mm f2.8) prime lenses.
I found that by using prime lenses, we will be forced to learn how to design the composition very seriously. When using a zoom lens, I found myself more limited to those standard styles of framing, what I mean is that, I will try to encapsulate some background to an extend such that they are just enough to record the context of that snapshot. It's very real that it's quick and simple, but again, it's just quick and simple, but in the lack of creativity.
However, with prime lenses, it's another story entirely! Prime lenses usually have bigger aperture (faster focal ratio to be exact), and thus, you can have more control on the depth of field. This is certainly another great way to control your composition, you can design how much you can put into "focus", and therefore, to dilute the effect of the background framing.
I hate to say this, but in the days with heavier air pollution, it could be a good trick to hide the dirty stuff.
Prime lens have a fixed field of view, but by moving yourself forward and backward, you still have some limited control. Since you have to move, you will be more serious when doing the decision. And with such limitation, you will be forced to be more creative. To give a simply analogy, please think about this scenario: if you have unlimited resource, you will not be very creative.
With a zoom lens, you won't move too much usually, so that's another kind of limitation to your creativity. But with a prime lens, you will be prepared to move always. Remember that by moving, you are not just changing the field of view, but also the shooting angle! And that's where creativity comes in. When you're more willing, or prepare to move, the more flexibility that you will have.