Why would you use Ubuntu with it's repository of stale packages and over-engineered package system when you can use pacman on Arch? On Ubuntu you end up having to add a bunch of PPAs if you need up-to-date software for any reason, then it's a nightmare to maintain. People just use it because of its convenient point and click interface and config utilities. Why should I learn to use a mouse even though I'm a command line ninja? No thanks.

(Note: satire. I use and love both Ubuntu and Arch.)