Yeah, I came to the same conclusion... I managed to install Infopath 2010 on top of my 2007 installation and I am now able to edit 2007 forms with embedded Jscript code from the old version. Although IP 2010 has some nice new features (such as filtering in web enabled forms and the "copy rules" feature) I am quite disapointed with Microsoft removing basic features. Such as being able to double click a control, in order to display its properties, and the missing Jscript programming of course.
I also miss the feature of being able to move data sources by drag and drop in the Data Sources panel (which is not possible in the old version either).
So far, I have found myself switching back and fourth between the two versions, which I would not expect should be necessary in first place - ideally I should only need one version of Infopath in order to edit any form: the newest! There is a small place for improvement Microsoft.