I missed the keynote, but according to the OP the release of Rails 5 means &quot;4.1.x and below will essentially be unsupported&quot;.<p>My advice is always to upgrade 3-6 months after a major or minor release. After 3 months so that other people have exhaustively documented their troubles and resolved incompatibilities in the libraries they maintain. And before 6 so that Google results for common issues are still fresh.<p>So I think putting it in terms of &quot;just because&quot; is not really very helpful. In a sense my upgrading in the 3-6 month interval is &quot;just because&quot;, but doing it this way keeps the overall maintenance burden to a minimum, since I do have to upgrade sooner or later in order to receive security updates.