Lifestyle choices should not interfere with a person's ability to do their job. Having a baby is a lifestyle choice.
It becomes inappropriate when the accommodation is not used for the reason it was intended, and when additional time is claimed to be required (outside of what was already generously allotted to pump) and approved and you're caught using this time extra time to instead to have extra breaks to rest, read, eat, check your cellphone, etc... forcing your colleagues to take on a lot of the care of your patients. I suspect that the travel nurse the OP wrote about may have very likely been at their wits end for being taken advantage of. Who really knows?!
Having a baby is a lifestyle choice. So, people need to be responsible for themselves and contemplate and reasonably try to plan how this choice will impact their lives. At the hospital you are not the patient, you are not the priority and while you are at work your patient deserves your attention. If your priority at work is your baby over the care of vulnerable patients who depend on you, perhaps you're not ready to come back to work?
Having a baby doesn't exempt anyone from being responsible for their nursing duties. No one should be responsible because someone chose to inconvenience themselves. I worked while I was a caregiver to my father while he was dying from cancer, but when I was at work I did my bloody job and didn't make my coworkers suffer because my life changed. The difference is no one chooses to have cancer...
No ones time is more valuable than anyone else's. Career professionals need to be respectful of their colleagues time, and reciprocate when people go out of their way to help them. The law protects nursing mothers, this is true, and I've sadly seen many women take advantage of this as an opportunity to get away with lighter duties or take their sweet time on frequent/excessive breaks when they were fully capable of their patient assignments.