Good, thought-provoking article. I'd make one slight correction: my understanding is that it is rotating shift work / nights that has been associated with an increase in health problems as mentioned in the article. I don't believe the shift work of day hospitalists (7 am - 7 pm) has been linked in a similar way, unless I missed an article somewhere.
Why do med students love EM? It's fun as hell (or seems that way to most med students). You put up with the social nonsense, but you're on the front lines of medicine. I may be biased because my school's ED is fantastic, but the ED rotation here was among the top two or three consensus favorites among students in my class. The personalities in general are great - if you have to stereotype a field, ED guys tend to be laid-back, fun to hang out with and learn from, and most have interesting hobbies/interest outside of work.
Why did I choose not to do EM? The rotating shifts. I can handle day shifts (like hospitalists) or even working a week of nights once in a while, if the hours are set. But most ED models that I'm familiar with seem to have constantly changing shift start/end times. I know how I personally function on that sort of sleep schedule, I talked to several ED attendings, and I decided it wasn't for me. Most med students should have access to honest attending advisors - and not just the early 30s attendings fresh out of residency, but the 55 y.o. ED doc who may be able to give a more balanced perspective on the field. But may med students - especially in their mid-20s - just have a difficult time looking too far into the future or predicting what their priorities will be 15 years down the line, and I suspect that leads to a lot of job dissatisfaction.