Damn Django is pretty hard at sunsetting old versions. If they are going to release a new one in October and only supply security upgrades to things that are two versions behind, does that means you have to upgrade your system in less than a year?
The last LTR was Django 1.4 which will be supported until October 2015. The new LTR is Django 1.8 which will be supported until at least April 2018.
Django can move ahead and drop support for (honestly very outdated) Python versions like 2.5 and 2.6 so that newer Django releases can take advantage of additional features and nicer syntax in newer Python versions.
And companies stuck on python 2.6 because that's what's bundled in whatever version of RHEL can still get security patches to Django.
It's unreasonable to expect the (volunteer) django maintainers to indefinitely support every version of python or every version of Django.
And if you have no choice of upgrading to Django 1.5 yet, I'm sure you'd rather continue to get security patches until you can upgrade to 1.8.