These are just a sample of the issues in psychiatry and the limited training received in psychotherapy (I'm on my phone, so I'm limited on sources. I'm on a computer hiatus until I am done with my break from my research). I've found a number of postgrad programs that expand on the limited training received in residency (elective was a bad word choice, it's more of a choice to pursue further training in therapy than what is offered in residency). I would suppose during residency it would depend on the program, but I know there are many, many other aspects of residency that have to come first.
Clinical Psychologists start from day one learning assessments and begin to work on psychotherapy skills with in the first year of grad school. They must have a certain number of hours doing psychotherapy prior to doing their final year (or more) of training as an extern. Between research and therapy, it's a very intensive program.
The benefit to having a psychiatrist is the ability for the psychiatrist to differentiate between psychological symptoms of a medical condition versus those of purely mental health dx. For example, Boys Town uses predominantly Psychologists and LMHPs for care, but a Psychiatrist follows via notes from these practitioners and follows through as needed.
Half the problem with healthcare is the fact that there are these constant battles on who is better... A physician or another type of training. It is silly, really, because it comes down to the situation. What might work for one person may not work for another. Saying a psychiatrist is far superior to a psychologist is pointless, as they all have their place in the system. All that matters is that a patient gets the right care for their situation. It's the same argument being had between a PhD nurse practitioner and a Dr. over who gets to be called Dr. and who doesn't. Personally, I've had better luck with NPs than Drs in getting good medical care for my Diabetes, but my Dad has wonderful physicians for his ALS. It's all about getting what you, the patient, wants in a HCP.