It's not odd, it's the result of false marketing and frankly very much the direct fault of publishers. They spend an untold amount on promotional campaigns showing prerendered footage, gameplay running on workstations with unrealistic specs, and buy endorsements. All together that makes people invested and makes them expect too much. It's very easy to feel lied to and betrayed when the final result doesn't even closely live up to the promises. It's even worse for sequels, as they inevitably get compared to the original by its fans.

If the promotion wasn't false advertising there would be no backlash and people would act rationally, as you say. Nobody hates on something they've never seen before unless somebody tells them to expect more than they'll get.

Thanks for adding some clarity. I can understand a complain about false advertising. I thought a major part of the complaint was game development focusing on graphics opposed to gameplay, which makes less sense to me.

I still don't get buying a game primarily for the graphics without looking at representative gameplay. I thought it was generally understood that promos and ads would show the best.