If you were wondering why Harmonix' upcoming rhythm game Rock Band 4 is not coming to PC, it's all down to piracy. Not piracy of the game itself, however, but piracy of the songs within the game.
According to Harmonix' product manager, Daniel Sussman, there are a range of security issues with the open nature of PCs that don't sit well with music rights holders. The rights holders essentially want the songs in Rock Band 4 unaccessible to music pirates, and the closed nature of the Xbox One and PlayStation 4 platforms provide this security.
Sussman does admit that the PC's security issues aren't an "unsolvable problem" - Harmonix could build a DRM platform to protect the songs on PC, and the company says this is "not off the table for the future" - but for now they are focused on bringing the game to consoles.
Music piracy isn't the only reason why Rock Band 4 won't be coming to PC. Sussman also stated that as previous Rock Band games never made it to PC, the library of songs that were available on consoles and that gamers may have purchased wouldn't be there. It's also unclear to Harmonix whether there is a market or audience for Rock Band on PC.
If there is enough demand for Rock Band on PCs, Harmonix may look to bringing the game to the platform in the future. For now, Rock Band 4 will launch solely on Xbox One and PlayStation 4 later this year.