Most likely because people expect to see it but few use it. So now the few who still use it will be surprised (pleasantly or otherwise), word will spread, and p

Most likely because people expect to see it but few use it. So now the few who still use it will be surprised (pleasantly or otherwise), word will spread, and people who didn't use it before will start using it again with the new functionality. So instead of removing a classic UI element of the classic Google homepage they just changed the functionality. I think that's logical.