Thanks for the replies, but I think you all missed my point: IMO it's a very stupid design decision to make age-old content the prerequisite to new content. Do I need to finish Eureka to enter Bozja? No. So why is PoD needed to enter HoH and EO? And I'm pretty sure I'm not the only one who struggled in PoD, and thus will never gain entry into any other DD.
The DD mode as itself does not interest me, so I really see no reason to even try (except that one time for the Moogle event, where it just was not worth the effort - sleepwalking 7 times through Praetorium gave the same amount of moogle tomes, and never fails).