Uncomfortable is being in a state where you are struggling against something. That thing is in your way and you need to get it out of your way to be comfortable.
Once you are comfortable, you seek to want to stay there. Why make that effort to be uncomfortable? Why be in a position to not know or to question?
But one should actively seek ways out of the comfort zone and back into the uncomfortable. By being there, you struggle once again. You are against the unknown. You are forced to come up with answers.
In short, you are growing. You are learning how to fight yourself out of uncomfort. You are coming up with answers you didn't expect. You develop self-confidence in your ability to battle your way out.
Most people don't normally like being uncomfortable. It feels unnatural and wrong. Uncomfortable is bad.
But uncomfortable is the natural state of the world. Most things are in a state of flux, constantly moving and changing. Fixed states are an anomaly in the natural world. Entropy is the norm, not the exception.