In T219403: Remove jquery.ui.spinner removal of deprecated and unused jquery.ui.* modules started, so I think it's a good idea to continue. At least jquery.ui.accordion seems equally unused (https://codesearch.wmflabs.org/search/?q=jquery%5C.ui%5C.accordion&i=nope&files=&repos=, someone should check gadgets).
A similar group of modules is jquery.effects.*, which has only very few uses (https://codesearch.wmflabs.org/search/?q=jquery%5C.effects%5C.&i=nope&files=&repos=), leaving many of these modules completely unused:
Together, these use over 500 bytes in the registry that could be saved.
Perhaps even more of these modules can be removed, some have just one or two uses which perhaps can easily be replaced, especially for effects.