It's for the cases when you are in a different timezone than the server. When the log says "03/Mar/2013 09:24:13 -0800" and it's 13:50 where I am, it takes me a while to understand how old that line is.

Right, the server says its timezone is -0800. You don't know what timezone you are currently in?

I know it's different, meaning that I have to do some basic arithmetics to get the log line age. It also requires me to roll my precious eyes to look at the local time in a system tray. It's just all too tedious.

Some services, like squid have logs with the time in UTC seconds...