It would be nice if the drop-down list provided by the KeywordSuggestPlugin showed a list of individual keywords. For example, in my installation I see:
However, I think it would be preferable if the entries where parsed according to the parameter multipleseparator. If multipleseparator = ', ', then my suggested keywords list would be:
If the KeywordSuggestPlugin were working with the TagsPlugin, then this list could be drawn from the TagsPlugin.
Overall the functionality of the KeywordSuggestPlugin might look more like the AutocompleteUsersPlugin.
For other tickets dealing with TagsPlugin integration see also: #4201, #4241, #3816.