What they repeatedly opposed was rushing generics into a v1.x build as that could break things.
The real issue is that many of the "haters" (and I hate using that term but it really was largely just individuals who decided that didn't like Go from the outset anyway so weren't exactly day to day Go developers) didn't think the slow and methodical approach was good enough.
Sometimes it feels like those who are the loudest critics of Go aren't even Go developers and instead just like to shout about how amazing their preferences are because it does xyz differently. And frankly I get a little fed up with all the psuedo-religious zealotry some have towards programming languages. It's nuts. Yet that's exactly how many of the language-specific topics end up on HN and why many on here could be forgiven for not realising that the Go team have always been open minded about changing Go; they've just been stubborn about the timelines of such changes.