I do not think that 100-200 people in a room will affect any announcement.
Do you really think things would be any different if Sony revealed that in a video an dnot e3?
Would the Twilight Princess reveal been as memorable if it weren't for the incredible audience reaction? Actually now that I think about it, I guess "effective" was a bad choice of words. "Memorable" was the word I was looking for. People look back at that Zelda announcement so fondly not only because it was an incredible trailer(it was) but because the audience reaction was so insane. Miyamoto coming out brandishing a sword an shield to the cheers of the audience was the cherry on top. It will forever be remembered as one of E3's greatest moments. Same applies to what Sony did last year.
This Nintendo event, while I'm hyped for it, likely won't give us any moments like that. I guess I just wanted to see a large crowd of people in a room genuinely get excited about Nintendo announcements again