Back in the 90s, when Winamp was the only game in town, many of us got tired of messing with the interface to make it useable and efficient. Foobar pretty much was plain Jane vanilla, looked like any other window and had the basics so you could do other stuff and not fuss with the horrendous skin.
After all, you're typically listening to it, not looking at it, which was the point for me. Winamp's tiny buttons and such drove me mad.
No offline, he typoed the url btw. I use it because I'm old and miss the old web portal days like igoogle before they ditched it. I made my own page that simulates an igoogle-like web portal, very customizable except you can't, for some really strange reason, click the header of an RSS feed to get to that page's home.
Would be sorta meh for me, except I made a sub-page with only 1 column that makes the best start page for a phone I've ever seen, because I made it myself with stuff I want to see all at once when I start my phone browser. That 1 feature makes it worthwhile.