Your reasoning is sound Griffon, but I have a couple of corrections for you:
You are correct that Pilot is low compared to the PML, but for the past few years we have declined to take DEO ... did the training system all-of-a-sudden "open up" or has there been a planning error by the C of C?
I don't know what your experience has been, but under CEOTP there is no guarantee of time for studies. Yes, most units will provide time when they are able, and yes, they are responsible to monitor and yes, there MAY BE a period of full time studies, but only the monitoring is ensured.
Lastly, your assumption that attracting DEO candidates is difficult is a complete error, and I have the stack of files for wanna-be pilots to prove it. (I in no way intend the term "wanna-be" to be derogatory, merely descriptive ... these people want to be pilots)
MY theory (and it's just that, I have no special info or insight) is that some people who want to become pilots, but may not be able to afford it after having completed their degrees, choose to attempt to join the CF in order to get the training. Combine that with the cut-backs in the civilian airlines and the number of EX-CF airline pilots and it becomes an attractive way of beefing up a resume.
My theory regarding the attractiveness of ROTP to the CF is this - "Obligatory service" ... yes, in theory, it saves the CF money when they don't have to pay for an education (DEO) ... however, the CF being a volunteer service (in that, it's not mandatory for Cdns to serve), a contract is just that, a contract, and we all know there are several ways to get out of a contract. I know LOTS of ex CF members who did not serve their entire 20+ years. Obligatory service incurred due to education however, THAT is much harder to get away from (the threat of having to pay back a LARGE scholarship and salary is pretty convincing)
SO, there you have it ... Pilot training with a guarantee of AT LEAST a few years service afterwards, or pilot training with a 'promise' of a few years service afterwards (and the conflict of a lot more money being offered civvie-side to entice the newly graduated)
Now - for all of the pilot applicants out there - again, I do not intend the term "wanna-be" to be derogatory, nor do I think that everyone is out to screw the system by getting their training and running away ... I am simply explaining HOW the CF MAY see ROTP as a preferred system to DEO when it comes to high-profile, high cost, lots-of-training, lots of civvie competition jobs. I'm sure that everyone feels that they are in it to serve their country and have every intention of completing at least their first contract, if not make the CF their career for life.