Just an update for everyone. I submitted a bug report for this Sort by creation date feature and got a great reply from a guy at Adobe. Here's what he said:
"This is one of our top feature requests, and we hope to get to it very soon. The reason it's a bit tricky is that metadata like the creation date is stored in the media file and having to read every file during each sort is currently taking way too much time, otherwise, we'd just turn on sorting. So we're working on it."
Great to have the actual reason and it make a lot of sense. I guess that in Premiere 6 this meta was not stored in the file, like it is now and that is why they used to be able to support this. So the positive side is that though they haven't found s solution yet it is conceivable they will - its not an impossible task just far from trivial. And when they do work out a solution it should also mean the rest of the custom metadata will then be usable in more ways.