As a maintainer, you're bombarded with reasonable requests (I think around 10 a day on the Go project). Part of your job is to turn down hundreds of these and pick the few that benefit the most people from a diverse set of users, and also don't break anything or extend the api surface too much. Then whatever you choose people complain vociferously. Sometimes good requests get ignored in that noise.
Choosing is hard, and while they could improve I think the Go maintners have done a pretty good job, and are willing to admit mistakes.
Admitting a mistake on "generics" would probably go a long way towards credibility for the team.
No matter how many excellent decisions they've made that have delicately balanced opinions and tradeoffs, this one hasn't gone over well, and it's very widely known.
Choosing is hard, and while they could improve I think the Go maintners have done a pretty good job, and are willing to admit mistakes.