The fact that a game has to scale from XBO to XSX doesn't mean that it can't look next gen - it just means that you need to spend A LOT of resources on implementing such scaling in a way which would provide tangible visual (and otherwise) benefits for both ends of the performance target.MS said every first party game has to run on the Xbox One, so we should not expect next gen graphics from those. If anything it was at this event where we could have been seen next gen graphics because 3rd party developers are free to do whatever they want.
MS being MS (they need to sell these XSXs) and having the earliest access to their own h/w is in a rather unique position where this can and should be the case.