Namespaces are for big projects. Staring big project using namespaces when it's not even clear they'll be in 5.3 is an insane risk, nobody would do it.
Only 8 hours ago, one Jean-Phillipe Serafin wrote: "Many people have starting working on top level application using namespaces, so there will a very bad buzz over the php community if namespaces are ripped out..." and there were further objections on the grounds that namespace support has been 'announced' on php.net.
I agree with you that it's an insane risk, but that doesn't mean nobody does it.
- Steph