Hi,
We indeed moved away from mootools.
However, for backward compatibility, we kept the capabilities in HikaShop.
So for example, if you have the "carousel legacy" setting activated in your HikaShop configuration, the carousels you'll be configuring with HikaShop content modules will use the old carousel system of HikaShop which requires mootools.
Turning it off uses the new carousel system which doesn't use mootools and thus doesn't load it.
So it's possible that you're using old features of HikaShop that you didn't migrate to the new one yet and thus these are still using mootools.
The datepicker is based on jQuery from the start and doesn't need mootools.
Squeezebox is about popups.