An obvious point that allot of developers still miss (Sakurai doesn't really say anything new btw, but he's right, of course).
My theory has been allot of developers feel pressured to get something out there early to stay in the rat race but what they have at that point is usually too embarrassing (relatively) to show off so we get these weak-ass trailers that don't actually show gameplay. The Nintendo way really is the best way though - Total radio silence until you're near ready to release. I just get overloaded with information from everywhere otherwise and usually lose interest from early reveals. The practice seems counterproductive.