It's definitely coming! One problem we have is that right now, everyone has to use the same set of Python versions. And virtualenvs link to the specific point release of Python, for example to 2.7.6 rather than to 2.7. If we upgrade a specific Python version (let's say, 2.7.6 to 2.7.10) everyone's virtualenvs will be broken because you can't have two different point releases installed on the same system.
This means that if we install 3.5.0, we'll not be able to upgrade it to 3.5.1. So we're waiting until we're pretty sure that 3.5.0 is reasonably bug-free before installing it.
Of course, the proper long-term fix is to support different execution environments, so that we can upgrade the default system image to the latest point releases but people can choose to remain on older ones if they have virtualenvs depending on them. We're working on that (our most recent blog post is about some Docker-related work that is largely driven by that requirement). But that's a little bit of a way down the line.