If you set aside the qualification/experience issue for a moment (difficult I know!) the concept of a DI is OK as far as I can see. Given the way that the construction industry works now, and the likely work that people will do in their trades then breaking some down into separate areas makes sense.
If you are only likely to work on domestic properties then a large chunk of a traditional apprenticeship becomes redundant. To be honest some of it was a waste of time anyway IMHO. All that cutting and filing nonsense, not to mention spending a few months in the stores etc.
It's the way all trades are shaping up now. Take plastering as an example. Time served back in the day meant that you could apply lime or gypsum based material onto boards, lath and browning etc. Screeding floors, rendering walls, making covings etc etc etc. All went together in a four year apprenticeship. Most plasterers training today will only apply gypsum based skim to boards with occasional use of bonding coat first. So the training has changed to reflect the separation of rendering from plastering and making them into separate disciplines for example.
BTW, the apprentice trained spreads that I know are all very pi55ed off about "short course" merchants undercutting them on price, and not having a clue about the full range of plastering skills.
It's no consolation to anyone here I'm sure, but it's an industry wide issue not just the electrical part of things.