Part of the problem seems to be that Nullsoft was a small company, and they were used to doing their thing, their way. When AOL bought them, the styles clashed; Nullsoft's "brainstorming over coffee" didn't jive well with AOHell's corporate beast. When Gnutella was released, AOHell killed it (not quite in time, but still). Same with WASTE...and that nearly made WinAmp creator Justin Frankel up and leave. He hung on long enough to finish WA 5.0 (making the comeback for the position lost by crappy WA 3)...but, now, they're all gone.
I'm sad to hear this, as WinAmp has been, IMHO, the best of the best for a long time. On the other hand, I'm glad to see it close down before AOHell really got into it.