It's tough for me to get angry about downgrades as it seems like a reality of the industry.
Developers are creating these videos two or even three years in advance, development priorities can shift wildly in that amount of time. For example, 6-8 months before launch there are critical systems that need to be reworked or the game just will not ship. You better believe that they are pulling people off of graphical features to complete the game on time.
Best case scenario would be for publishers to be more open about it. I know that full disclosure isn't what they do best, but being open and honest about some visible changes would probably help their situation.
I dont mind downgrades in that sense, I mind lying