They didn't disable it, they just moved it. All api requests that don't require authentication are now at data.mtgox.com instead of just mtgox.com. Supposedly this will help the trading lag since a separate server is now handling data spewing.
I'm astounded that it wasn't separated onto multiple front end servers in the first place.
Mtgox has a shitty setup from a technical perspective. They claim some big improvements are coming, but I will be surprised if they are able to keep up with bitcoin growth. In fact, I hope they won't so we can have a more distributed exchange scene.