Mobile devices are - and have always been - about tradeoffs rather than maximizing specs. Each device is designed to achieve a balanced solution to a specific scenario and set of priorities.
In this light it would be smarter to not fall into the trap of A vs B comparisons. I dont know why so many tech forums are full of them.
Also the tablet market is basically the new PC/laptop market. People instinctively understand that the use case for a 17" MBP is different to that for the MBA, the 15" MBP and so on. What's big deal then with having an iPad Mini and an iPad 4. They are simply different slots in a product line, segmented based not on price point targeting (that is what the 16GB Ipad 2.4 is left in there for) but rather on providing different solutions. Not less valueable and more valuable, just different type of value. Smaller doesnt have to mean less valued (ie lower price) in the eyes of the consumer. Heck, personally I've been buying ultraportable laptops for a decade plus now and I have always knowingly paid MORE for smaller computing packages with "worse" specs.
I like the Ipad Mini - its a well thought out product. It is crippled deliberatelty, one has to be honest about that (then again IOS in general is full of deliberate crippling, so no surprise there) but nonetheless its an incredibly portable package and much easier to handle than the Ipad4. The Ipad 4 has great performance, but is unwieldy enough to show clearly that we are bumping up against constraints in the form factor/weight possibilities, so new solutions are needed there.
My guess is that once the tech industry figures out how to minaturize/weight reduce these things some more, Apple will settle on having a Mini at this 7.something screen size, along with a much bigger flagship tablet, which may use the foldable screen concept tried out a couple of early tablets (Toshiba Libretto series had one of these I think) from a several years ago.
No either-ors please - this is all part and parcel of ultraportable computing: a constant push-pull, form factor development and so on. Its what is required to meet the potential of the product and the variety of use cases.