Let's say we forgot how to do heart transplants. Once we did them a few times perfectly, got all surgical techniques right, but patients died shortly after the surgery due to rejection. We quit the whole transplants stuff for years, the techniques and the equipments were lost over time. But then, some 40 years later, we now knew a lot more about immunology, have incredibly advanced drugs, and an aging population. So, because of that, we decided to develop the surgical procedure techniques, long-lost, again.
This is a good analogy for the situation. The moon is an important milestone for further commercial and scientific exploration of the space. We lost the ability we once had to reach it. And anyway, we were not as ready as we are today to follow the next logical steps. If we manage to harvest water from moon ice now, we will be establishing the basis for a kind of serious exploration and development that we weren't nearly ready to achieve in the past.
So, no, we are not doing it just to prove "we haven't lost our mojo", for bragging rights. We are doing it because we are in a development stage where it makes sense to finally return to the moon.