The problem is that in some jobs, and apparently the one this woman was hired for, the timing is part of the ability to perform the job. Accountants, for example, know that they're working non-stop from Jan-April. If you're hiring someone for that job specifically because you need someone around at that time, and then find out they're not going to be there, it does make them, well... a bit useless, at that time, for that purpose.
But if you were in the UK and taking the full 52 weeks you were entitled to, you would miss the busy period at some point no matter when you timed your pregnancy.
Maybe this woman in the US was above and beyond the highest qualified for the position and the hiring committee recognized that they would be lucky to have her, regardless of whether she would miss the busy period for the current year (after all, there is always next year, and the year after, and the year after that...).
There will ALWAYS be busy periods each year at any job--I don't think it's right for anyone to expect a woman to have pregnancy planning down to an exact science just for the sake of not inconveniencing her employers.
I just learned from a friend that the University of Nottingham has recently announced they will offer fathers an additional 26 weeks of paternity leave which can be taken beginning 20 weeks after the baby is born--presumably, so the mother and father can equally share in the responsibility. I wish more employers would start offering something along these lines--if fathers were able to take a larger amount of time off after the birth of a baby, women could potentially return to work sooner if they wish and perhaps the stigma surrounding pregnancy wouldn't be so severe.