Which still doesn't mean that they're overpriced
Value is in the eyes of the purchaser. For me, the aspect ratio of the iPad Mini was worth the extra £100 over the Nexus 7. For others, it may not have been. This seems to be the point you're missing.
Yup, the screen size and overall product size/ feel in the hand is also the reason I went for it over a Nexus 7.
Its the only tablet I've played with that actually feels like startrek tech. I know that sounds geeky but its thinness and screen size really remind me of the tabs seem in sci-fi programmes. The nexus 7 on the other hand is thick in the hand, has a much smaller screen and is a big lump of plastic, not a just two pieces, a piece of aluminium and a piece of glass. Not to mention the Nexus 7 would be more expensive if Google weren't using it as essentially a loss leader. Depending on what you read they either aren't likely to make much or are making a loss on it... It's to persuade everyone to buy into their ecosystem.