I'm not positive, but it sure looks like it. It appears the only way to accomplish a datum on the fly is to pause the feature creation and create a separte datum that appears in the model tree. Then resume the feature creation. This creates a group with the feature and datum in the tree. If you want to change a dimension of an offset datum created on the fly you can no longer just select the feature, you must select this datum from the tree. And this is better? I don't think so! Am I wrong? Someone tell me if there is a better way.
you can double click on the datum plane and type in a new value. I think the problem you are having is that the datum is hidden by default, so you have to unhide it before you can click and modify it. * right click>unhide
I like the way it works now, I use a ridiculous amount of datums and its nice to not have to set up specific layers to group them.
The datum is not exactly hidden in a feature...it's a group, so if you need to group the feature with some other features you must ungroup and then re-group(you can't group groups). This is another reason I don't like it. The truth of the matter is I don't want to see the datum and I don't want to search for it in the model tree! Pre-Wildfire releases kept it simple and internal to the feature itself.