this debate goes on all the time.
My thoughts are : (and I'm biased, did a 4 year)
We do emergency medicine, which is a mixed medical/surgical specialty
we are required to learn a good number of procedures as well as critical/complex medical pathologies/emergencies.
medicine does 3 years with a bunch of fellowships
surgery does 5 years (ENt, ortho, urology, optho, gen surg)
Anesthesia which is almost close to our speciality does 4 years.
It doesnt' seem unreasonable that in order to learn the whole breadth in training 4 years would be a better suit for the field.
will you lose money doing , yes but that should not be a determinant of training.
Will you be a competent physician after 3 years in EM? yes, a lot would, but from my experience, I'm not so sure that we are not graduating some folks that are questionable.
How would a 4th year general surgery resident fair if they graduated...they would PROBABLY do ok, but they do 5 , because thats what they feel is necessary to train MOST residents. Obviously there is a limit to this logic, but do you see my point?
I just think if we want our field to be more respectable, it makes sense we should be 4...
Again I'm not saying someone from a 3 year residency is NEVER better than someone from 4 year, I've seen both ways, even were a 4 year resident may not be as good as someone from 3 years, but I'm talking about residency length for everyone.