It's not the same. It opens the mini player, each although shows a bigger artwork, doesn't have two features the previously separate artwork viewer had, namely,
- You could resize it to any size whereas the mini player doesn't resize as big.
- It could be invoked when iTunes was full screen. Now it requires Music to be not full screen or it does nothing at all.
I can understand some people not caring about it but I've a lot of music where I replaced original artwork with higher resolution files just so it could look better when resized to be as tall as the screen and I really miss it especially when shuffling something where just a glance at the screen would let me know if I'd like to skip the track or not.
Also, totally agree with you that the missing column bar is such a bummer! There's simply no replacement for browsing a lot of music moving from artists, albums, genres and composers so quickly!