Youre right and there is no disputing that. I would add that it is mostly because MS was saying so many things basically adding up to prepare to have your mind blown and literally saying be ready for a night full of mic drop moments.
saying that, if that doesn't happen,.. well, there is a reaction based on what happens when the perception is that the company was just full of hot air.
Sure, there was good stuff in there, but... in business there is a good rule to follow. Under promise and over deliver. That did not happen.