My 'favorite' explanations for the low propensity to do a Doctorate in Accountancy in Europe are two. In addition to poor design. These two will no doubt also draw comments. Evidently, there will be other causes.
1. A narrow attitude among European accountancy faculty regarding the aim of an Accountancy Doctorate. That keeps the number of doctoral candidates in Accountancy low. The 'holy' aim of most Accountancy professors is for all new Doctors to go into academia and to do well there. This attitude is conceited. Why is being smart and innovative in industry less desirable. Nowadays it also misreads the times. A EU Lisbon and then Horizon 2010 goal is for new European Doctors, the new ISCED 8 graduates, to also end up in industry. Smart people are expected to do great things there as well. Indeed for Marie-Curie-Sklodowska Young PhD researchers, preparing them for a possible career outside academia is a requirement. I see a role in this matter for the EAA. Convince the community to be open minded about non-academic careers for new Doctors. One way to do this is to open the Madrid Talent Workshop for non-academic recruiters.
Of course for careers outside academia there must be a demand for the new Doctors there. Accountancy practitioners tend to be strangely unintellectual with regard to their own field. Same story for standards setters and oversight bodies. I see audit firms recruit a large numbers of new Doctors. But not in the area of Accountancy. These hires are in new technology and data science. The same will be true for oversight bodies soon. Here also the EAA could act. Work on this issue with the body that represents the Accountancy profession in Europe. It recently changed its name to Accountancy Europe. They also are based in Brussel. This is their informative website: https://www.accountancyeurope.eu/
2. My second explanation is that the BSc in Business, and the MSc in Business as well, are not academically challenging. Compared to nearby BSc and MSc in Economics, or Psychology, for instance. The effect is that the Accountancy BSc and MSc students will have a hard time discovering that areas such as Accountancy are intellectually challenging. This has 2 reasons, one of them self-inflicted. That self-inflicted reason is that Bachelor and Master programs are cash cows for Schools. Making the program more academically challenging is risky, student numbers may drop. The second reason is, for Business students with an interest in Accountancy, is that the Accountancy profession has a tight grip, handed to them by standard setters and oversight bodies, on the accountancy content of the BSc and MSc programs in Business. This leads to very early specialization and rules oriented courses in accountancy in these programs. On this also the EAA should engage with Accountancy Europe and with Accountancy regulators and oversight bodies in Europe. For instance the newly formed CEAOB. The CEAOB groups the national accountancy oversight bodies in the EU: i.e. will be the European PCAOB. They do not have a website yet, as far as I can tell. So google CEAOB to find out more. Note that convincing the Accountancy profession to loosen its grip on the contents of BSc and MSc programs in Business, allowing a move from topics courses to theory and methods courses conceptual, courses will (1) spur intellectual curiosity among the students and a much higher interest in doing an Accountancy Doctorate, and (2) make an MRes Accountancy much easier to organize. A 1 year MRes in Accountancy, or a 1 year research track in a 2 year MSc in Business or Accountancy, would become possible.