I guess it's because Apple removed a useful feature, with no reasonable upgrade path, even if you do have your old data?
I could have written a similar article about the upgrade to Xcode 4 - but, because I'm a relative newcomer to this whole Apple "thing", perhaps I'm just more acutely aware how useless it would be, if I told anybody apart from Apple about this (radar bugs: 11405857, 11252538, 11207936, 10985344, 10779669, 10596415, 10596323, 9624250), because you just don't get any sympathy. And I didn't even use Xcode Interface Builder plugins!
I could have written a similar article about the upgrade to Xcode 4 - but, because I'm a relative newcomer to this whole Apple "thing", perhaps I'm just more acutely aware how useless it would be, if I told anybody apart from Apple about this (radar bugs: 11405857, 11252538, 11207936, 10985344, 10779669, 10596415, 10596323, 9624250), because you just don't get any sympathy. And I didn't even use Xcode Interface Builder plugins!