In short - I had a lack of reliable traffic nodes and my bachelor's degree to finish off.
Now, the long version.
The university reason is easy - I've been working on and off on a Bachelor of Arts for a few years, and decided late 2009 that I should just buckle down and get it all done. So I spent 2010 and the first part of 2011 studying (and working!) full-time. It was pretty intense. I had to put a few things on hold, and working on cacheboy was one of them.
The traffic node problem is more difficult. I had plenty of interest in running edge nodes in places like Australia, Italy and South Africa - where local connectivity is great, but international transit is not. But in order to run any useful amount of traffic from those nodes, I'll have to serve a lot of content to the network as a whole. This means "US" and "Western Europe".
I found myself in a catch-22 situation. I'd like to serve content across local IXes, but in order to do so, I first need to serve a lot more content to the US/Europe.
In order to do this, I'll need a few reliable nodes pushing at least a gigabit each. The last time I ran the numbers, more than 70% of traffic was destined to the US, UK and Germany.
So to properly push proper CDN of open source content, I'm going to need some donated nodes in the US that can source at least a gigabit. If I can't get that, the amount of traffic served to other destinations which could benefit from local traffic is .. well, it's really quite small.
So far, noone's stepped up to help with that.