Spotify’s “Play” button is an unfortunate hack.
In the same way that Google’s “Onebox” play button that was momentarily embedded in search pages (remember 2009, anyone?) was a cruddy hack. although somewhat less of an unfortunate hack than Spotify’s.
So, what’s the problem? Well, everything comes in three’s so there are three parts to this problem.
(1) Music is so much a part of human culture these days, of web culture no less, that the necessity of playing the file through the Spotify app is ultimately of function of a copyright problem not a technical problem. We should not have to jerry-rig technology just so we can fit within the eye of the copyright needle. Copyright law should adapt.
(2) and somewhat related to (1), The play button requires that we experience a technical inconvenience in order to work—confirm you have Spotify or you must download the app to hear the track. That’s annoying. If the play button is on the page, all we should have to do is hit play.
(3) It could lead to the same sort of Highlander effect—”there can be only one”—that the music industry now finds itself whinging about, in regards to iTunes. Tactically, the play button is ideal for Spotify. First, the service has a way to virally spread beyond Facebook, triggering downloads of the application. Second, the method for embedding provides a way to minimize competitive creep, since partner sites will probably not want to have 2 or 3 or 4 embedded “Play” buttons, accommodating the 2 or 3 or 4 (or more) services that are out there.