This very thread is the reason why. Things just don't simply scale by turning down resolution a notch. They will have to build their games around a slow HDD and a terrible CPU among all the other outdated hardware.
You might never get a game that runs terrible from MS first party but that will because they made probably significant cuts and sacrifices on game design and gameplay in order for the game to run on the Xbox one as well.
We will never know what those games could have been and what we are missing out on it's as simple as that because just lowering resolution is not a solution.
Then why waste time even worrying about it in the first place?
and this thread is based on some rumour, nothing official at all.