The importance of when
Any time a given Drupal core development cycle is more than six months old, people start asking "When will Drupal X be released?" The answer, of course, is always "When it's ready. Please help us finish it." That's well and good, and I don't propose that we change that position. Volunteer labor and fixed release calendars do not mesh well.
However, knowing when Drupal will come out, at least in a vague sense, is increasingly important for core developers. The web is changing rapidly, even more rapidly than it has in the past, and knowing what the web will look like around when Drupal 8 is released is critical. Not only so that we can target the right features to get ahead of the curve, but so that we even know what our available tools are.