I'm not sure I agree. The interview process is stuffed to the gills with Billy-Big-Deal trader wannabes. I find myself doubting the sincerity of many people who say they want to be in finance. Middle- or back-office experience would suggest a sincere interest in the business and not simply a sincere business in making a quick buck.
You have some points on the value of MO and back office work.
All else being equal, it's better to prove interest in finance than not prove it. All else being equal, it's better to prove that you can get a front office job than not prove it. But I think much of the interest in finance is proven with a $80K tuition check and two years of your life. So the question is, does an MO job help you more on top of the $80K check at proving you're interested in finance, or does the FO job help you more on proving you can land in the FO?
And the cynical voice in my head is saying that schools care more about placements than whether people are actually interested in finance. If a JPL Rocket Scientist decides to go back to SpaceX where he is getting a $700K/year offer to manage launches rather than earn $200K/year in finance, that boosts average first year comp and allows the program to say "Here's what happens to our graduates who DON'T get a job in finance" with a wry grin on its face.
As long as about 2/3 of students make a career of finance, data science, statistics, or something related to an MFE, it's OK for the other 1/3 to go out and prove that MFEs/MFins/ORFE people in general are just as capable and versatile as MBAs.
Stanford GSB had some MBA graduate to earn $530K his first year in Private Equity and a lot of people were talking about that. I know MFEs who have earned on that order their first year, but it would really be quite a shock if one of the ~1000 MFEs who graduates every year winds up earning more than one of the ~6000 top tier MBAs who graduate every year, even if his work is only ancillary to ORFE. It would also prove a point to some of the dumber hiring managers out there and open more MBA-type roles to MFEs.
So if someone could graduate and earn substantially more outside of finance than inside of finance, and it was a STEM-related role that occasionally involved stats or stochastic processes, I think it would help a program- and help the reputation of MFEs in general more than it would hurt.