Andy, your question is one of the reasons I started this thread
First, I want to mention "great career service from PhD programs". There are few problems with this. The area of PhD and its educational nature determine the kind of career service you get. Most of your networking and career service advices are related to education. When I was at Florida, most of the positions advertized were at various
universities across the World. Also besides universities, you get to know about positions through personal contacts of professors whose interests span certain areas. So, if most people in your department are interested in Biostatistics, then most of the positions you get to know about from professors are in the
area of Biostatistics. Therefore, if you are interested in working at a university in the area of Biostatistics, career services help is there for you. But if you decide to go work on Wallstreet, then the school won't help you
unless school contacts are also working on Wallstreet.
However, if you already have PhD and interested in Finance, there are thousands of employers looking for you, and you might be able to find a good job without help of your school.
If you go for an MFE, then you get an excellent training in Math/Finance/CS and career help from your MFE school.
What I would like to mention here is the kinds of jobs you can get with MFE and PhD. And this is where I might answer the question why "PhD after MFE". I won't go into details about the jobs, just want to mention that I'm personally interested in those that happen to require PhD. I had a job intereview long time ago where they told me that they were looking for a Quant Modeler (or someone similar) and preferred the person to have a PhD.
Also, in my case it just happened that "PhD is after MFE", I would prefer to call it "PhD and MFE"
My reason for getting PhD is that I don't view MFE as a terminal degree because some 10-15-20 years from now I see myself teaching, publishing papers, going to conferences, etc. But before I go teaching, which I very much like, I want to do something on the street. By
something I mean developing something of my own, and that something must be of practical nature.