All that ranting aside, BloodyIron, I need to thank you: In thinking about a use case for cross-fading (e.g., a DJ like system), I've actually designed in my head a basic DJ-type app that (using my hack of 2 audio tags, effectively each representing a record platter), might actually be able to handle the cross-fade and gapless. It would only be desktop-browsers, but a 'client' app could provide tablet/phone users the ability to see the songs played and make requests that could get automatically queued up (using the chat feature to pass JSON strings to the DJ app).
As an app writer, I've always been more concerned with the API flexibility and stability more than anything specific about the Web UI. I figure (and maybe Sindre does as well) that targeted applications and features may be best as just that: specialized in apps rather than crowding the already crowded main Web UI. We've gotten very used to players that are just that, players, but as I've written with the playlist "radio" generator (http://subfireplayer.net/radio/), there are other things the API can support than just yet another music player.
That said, I do agree with much of your earlier concerns with the risks of closed-source software, when managed by only a single person, as somewhat high. Should a tragic accident happen, we all have no way to carry on with our own collective investments except through the forks off the 5.3 branch, so much development from that point would be lost...and in time, the 5.3 code base (given its dependency on Flash in JPlayer, as well as the state of J2EE as of this moment in time) will not work out-of-the-box unless someone continues to keep it up. That's even without the security aspects and concerns. It isn't enough for me to move elsewhere (and I agree with Sindre's counter-concerns: the forks like Madsonic each collect their own license revenues but I expect little of that comes back to Sindre - the GPL or MIT licenses make that possible, but how ethical it is for those services is up to each to decide), but I can understand that particular concern.