While Old vs New standards is indeed a problem to be overcome by MoD on any old design and, indeed, "modern" standards tend to be more stringent in certain areas, I do not think this is the cause of MoD's systemic failings.
Rather, they should look to those who formally ruled that the likes of JSP553, Def Stan 00-970 and the procedural standards (05-series) could be completely ignored.
All you have to do is map the recommendations of various BoI reports (Nimrod, Hercules, Sea King, Tornado etc) to mandated requirements laid down in these Standards and ask why they were not implemented in the first place.
The same applies to Haddon-Cave's report. A 3rd year apprentice could have told you 90% of the content 20 years ago, in far greater detail; and the same senior MoD staffs who made the above rulings were told, with monotonous regularity, over the last 20 years.
It is not the state of the Standards that the MAA has to overcome, it is the ingrained ethos that they can be ignored if it means "saving" money or time; at the expense of safety. That, I am afraid, will take a long time. You only have to look at the senior staff list at AbbeyWood. The MAA and Bernard Gray will meet much resistance. No-one is going to put their hands up and openly admit "Of course I paid off (e.g.) Critical Design Reviews and then waived the need for the CDR". (But luckily we still have the paperwork as evidence!). The only question in my mind is how many years for such a fraud.