For that dev part they have the developer keynote. Google just gave away many online training classes for free, which includes many many hands on coding labs.
I doubt it's press who is the audience. People behind these projects want to be seen by SVPs and above, so they get those 5 minutes of attention, get their promos and immediately switch teams to chase the next promo.
Okay so it wasn't just me. The I/O event in the past always had much interesting content. I was surprised to find that not a single one made me even consider reading about it.
When they introduce new products, do they say "and really we won't abandon this in 2 years" and keep a straight face, or do they just not even bother?
When Google IO started it was a nice fun tech presentation with a lot of side classes showing devs how to work with these new google technologies.
Now, it's mostly just google introducing new products to the press.