This service is far too expensive to be successful. If they charged, say £40 for the whole pre-2005 Doctor Who catalogue, it could have been something I'd go for. £7 for a 6 episode serial? When I can purchase that same serial on DVD for £5? No thanks.
You aren't ever going to get 26 seasons of Doctor Who for £40 though are you? That would be 155 stories. That's 25p a serial. Or between 3p and 25p an episode? I doubt that would cover the artists rights - so the BBC would be selling at a loss.
The point of the BBC Store is to bolster the licence fee, just as DVD and Blu-ray sales do, not to lose the BBC money.
If that's the case those artists rights are punitive and need to be renegotiated. We live in the age of Spotify, Netflix, Amazon Prime etc. which deliver people the content they want for nothing then less than £10/month. People will not tolerate paying high sums for digital content which they have less rights to than a physical counterpart. The PC video games industry has got this right - places like GOG.com often charge less than £3 for older games, and these are DRM-free downloads, typically with any bonus content included.
If the BBC can't achieve attractive price points for their content the service is utterly moribund. I can't find a single offering on there which looks even vaguely attractive, even with 25% off. I can find plenty of examples of rip off's though - here's another standout one:
The Office Series 1 - £7.99 on BBC Store, £1 in any branch of Poundland
(or free/£4.99pm on NowTV; free/£5.99pm on Netflix)
The Office Series 2 - exactly the same
Presumably the price point has to be similar to that of iTunes to avoid accusations of anti-competitiveness and massively undercutting a commercial rival too?
Well I'd argue the price on iTunes should come down too, but I don't see why Worldwide should have to hold the same pricepoint on all the platforms they distribute through - no other broadcaster has to, and you can be damned sure that Apple will be taking more via iTunes than they do on the BBC's platform.