It used to be like this: Visit https://www.google.com/ncr once, and on further requests, https://www.google.com/ or https://www.google.com/?hl=en wouldn't redirect to google.de any more. Unfortunately, visiting https://www.google.com/?gfe_rd=cr&gws_rd=cr doesn't appear to have this effect. Still a good workaround, so thanks for sharing!

I wonder if this might have anything to do with that EU right to be forgotten thing. The EU would like Google to remove search results from google.com, which is obviously very undesirable for Google, so maybe they try to appease the EU by making google.com harder to access for Europeans? Maybe the Use Google.com link will be removed soon?