This is my argument against keeping them.
The Bug Squad and IRC council say "you should upgrade", and generally ignore them.
More specifically, the Bug Squad says "Try to replicate this bug on the latest stable and get back to us".
The questions about EOLed released that I've seen are all in the same vein - "How can I get software X on my 10.10". Well, the answer is ends up being (most of the time) this:
You have to compile python3 from scratch, and you have to get all of your dependencies lined up in a row just to be able to compile python3, and then you need the full gtk3 stack, and then we might be able to get you your software.
Or...wait for it... you can upgrade to the latest release, and save yourself all this trouble, and you're fine!
Quoting from another answer on another discussion about this:
On the flipside, the usefulness of EOL-specific questions falls precipitously as time passes, as does the population of people able to maintain them.
One of the greatest things about Ask Ubuntu (compared to the Ubuntu wiki) is that we try to keep things up-to-date. Things don't go untouched since 2008. I'd be hard pressed to find a answer that hasn't been touched since the first day of Ask Ubuntu in 2010, and have it not work. Why? Because people care about their answers. As soon as it no longer becomes relevant to the stable releases, we need to talk about it. And probably delete it.
I'm not saying that on the day it becomes an EOL release, we close it as off-topic and tell them to upgrade. I'm saying that within 2-3 months, instead of just pointing them to the "how do I upgrade" question, we start closing them. Grace periods are nice and useful in this situation.
As Jorge Castro says here in his lightning talk at UDS-O, too much information on the internet is wrong, and is hurting our users. And information about EOL releases is wrong for the vast majority of our users, and it will hurt them.
It's our job (as a community as a whole) to try and keep the information up-to-date.
Oh, and last thing: if I can't get security updates for things, why am I using this? EOLed releases don't get security updates.