BTW, the player buttons used to be in the top bar, and the search was smaller. I could not for the life of me understand why they moved it down...
I disagree with the comments suggestion - it's a feature probably stemming from the fact that the site was (is?) mostly used by DJs for uploading sets, and commenting on certain high points of the set is a cool feature.
But the biggest problem with their site right now is performance. A SoundCloud tab keeps the CPU consistenty busy. (And, interestingly, only when it is visible. When it's in the background, it's fine. Using Firefox.) And prolonged playing causes my browser to crash. I use both Spotify and SoundCloud, and Spotify has none of these issues. I presume the Flash player component is to blame.
Oh, and of course: "A new version of SoundCloud is available. _Reload_ your page..." And then you reload, and nothing changed. Every other day, sometimes more than once in one day...
But it's still a really great site, I love it.