my list of things wrong:
1) this is a useless feature that should have been deprioritized and the time used elsewhere
2) it should be a freeform text field, it's way more time/effort to make a list
3) now someone has to update the list because there isn't an "other..." option, increasing the time sunk into this useless feature
4) the 99% use case is not at the top of the list
5) nobody, and i mean nobody, knows that you need to command-click to select multiple items in a multiselect list