I'd like to point out that the search and how the results are displayed are part of the design - and can be the major bit. UI design isn't only, often not even primarily, about aesthetics.
It's possible you may need to redo UI for new search. If I add faceted search or geo search, for example in my search update, I may well need to redo the UI in a way much more fundamental than aesthetics.
UI design doesn't involve BE design in any way. So?