Yes, you're right, they did this a looong time ago... BUT, sometimes Google still insists on showing you results that don't contain the word or phrase that you've explicitly requested must be in the results - utterly infuriating!

You now have to go into Search Settings -> Verbatim. Unfortunately you’d have to do this for each search session as it doesn’t persist.

In Chrome, I've set up Google Verbatim as a search engine and made that the default address bar search. Here is the URL format: {google:baseURL}search?{google:RLZ}{google:acceptedSuggestion}{google:originalQueryForSuggestion}{google:searchFieldtrialParameter}{google:instantFieldTrialGroupParameter}sourceid=chrome&ie={inputEncoding}&q=%s&tbs=li:1

Especially when that word is 'not'.

Yeah, you are right; https://support.google.com/websearch/answer/2466433?hl=en

They even dropped tilde :(

But you might be able to achieve the same things with their advanced search; https://support.google.com/websearch/answer/2466433?hl=en