Because some of us want the latest specs, just not a mini design. They need to keep the current design and update the internals.
If they don't, then those of us who want to upgrade are forced on the new design.
As of lately, Apple's new designs are not innovating and the ip5 was a huge step down from the 4s. Just wish the 4S had LTE.
What about those of us who like the design of the mini and hope the iPad 5 will follow the same design. Apple need to change the design to match the mini.
If they don't, then those of us who want to upgrade are forced on to have a 3 year old design.