Google works hard (or maybe less) to keep their front page UI ultra clean. I do think users could benefit a lot from a small drop down arrow under the search field that stretches open another field to input the words searchers do not want included in their results. Most of us in the Hacker News community know this can more easily accomplished by including a "-" (minus sign) before such terms; we know how to use "-" and "site:..." to narrow query results. However, I'd say 50% of Google users don't know these tricks and waste time navigating to the advanced search link.