Could it be possible those interiors will be optional DLC ( since DLC is more or less confirmed ) as it appears they made the decision to release the core of the game on an already fully filled BluRay disc?
I mean if a track editor is included amongst all other new features the core of the game would be a similar experience to all from the beginning leaving only optional features ( interiors, driving suits, liveries, etc. ) or upgrades to be added by choosing or buying DLC.
Don't get me wrong, I was really hoping all cars were shipped with interiors from the start ( and this is much more than just a graphical discussion as interior view is a feature, imagine all previous GT's being only playable from 3th person view and Prologue offering bumpercam for the first time, all those bumpercam-junkies would cry outrage if it was only available on 20% of the cars in GT5.....).
My point is that it may be ( hypothetically ) possible they've already included those features destined to be future DLC and decided ( by choice or forced by circumstances ) the interiors, etc. could be percieved as optional and would be added later leaving them with more space on the disc to fill with those new features which all of us are going to use and giving them time to further model all those interiors for future DLC for those ( including me ) who care ( and perhaps willing to pay unfortunately for this optional but relevant feature ).
For those who only use other views, the game as it is would probably suffice.
Graphical distinction between Premium/Standard isn't the thing really bothering me, it's the lack of similar features, read interiors ( affecting the gameplay for me ).