Is it important? It was a cool program 30 years ago but it’s just a playback UI right?

It’s not the old program anymore, and it already leaked a long time ago. It was obvious that the new one wouldn’t be open.

The new one is just a web UI with options for streaming music. There were talks of the old original Winamp going open source though, which bought nostalgic memories to many. Eithercase, with so many music players on both Windows and Linux, I doubt Winamp would a niche case to fill.