I actually felt like this was the best quality opening they've had, along with the best quality finals match they've had. The most memorable performance for me will always be the S2 opening, but a lot of that is because it was a surprise and really was the eye-opening moment where you realize "wow, this is legit". And unpopular opinion, but I felt the Imagine Dragon's performance was extremely lackluster, musically speaking (either they had an off day or else they're just not that great of a live band).
I was super glad they had the live orchestra performance back for this year. Personally, I would probably still prefer if they did more of a throwback to S2 and made the whole opening happen with the orchestra as the main feature, but I also get that that isn't probably the most popular idea ever, so...
But I think your complaints with focusing on Zedd there in the middle are legit, and I think it was largely due to the camera work during the song. I'd rather that they remained zoomed out more, so viewers on the stream could take in the whole (awesome) 3D projection screen cube thing more. That, and the song itself didn't feel right for the occasion. It wasn't epic enough and didn't really give a feel that it was leading up to something that would be the culmination of a year of work for the two teams.