Here's my logic:
I would imagine the people over at Xbox are aware of the current console landscape in general and have reasonable expectations for Scorpio based on what they see. I don't think Scorpio is gonna be outselling the base model or anything, but the very fact it has an E3 presence means it's getting much more of a focus than the PS4 Pro did. The reason I think that's important is because even if the Scorpio ends up being great hardware, a bad E3 showing could drag it down considerably (which is why I imagine many assumed it would get its own event).
So since E3, the biggest stage of them all in the gaming world, is the place they chose to unveil it, I'm guessing that's because they want to take that oppertunity to send a message about Xbox's future, something thats often questioned, and occasionally for good reason.
If you look at a post from a couple pages back someone took the time to compare a chronological time line of a Xbox E3 presentation from the beginning of this gen to the most recent. One thing you notice immediately is the focus on third party games is increased greatly in last year's E3 presser and the problem with this is a heavy focus on third party games over first party leads to only one conclusion: a lack of identity for the core brand. That's been Xbox for years now. What words come to mind when someone asks you to describe what a "Xbox game" is? And while this has been an issue for a while now, I feel the cancelation of Scalebound was the straw that broke the camels back. Even around GAF, it's like it was a trigger for all kinds of repressed (and imo,deserved) MS focused rage and it's still here, slowly raising toxicity levels.
So it's not so much im expecting anything in particular, but more if they don't address the concerns here and now, mainly the lack of identity, the damage done to Scorpio could be measurable even if it does deliver. As far as I'm concered, a merely mediocre E3 would be a failure all things considered.
And that's why you should be hyped.