The search in kickoff is not obvious because it doesn't have any indication that you can search. It says you can with text that transitionally fades to other text. Often there are people who are unaware of the ability to search because they miss the fading text.
This issue could be solved with the search box made to look like a search box similar to how the minimal "kicker" menu does it.
Alternative Option: use the minimal menu by default in Kubuntu