Rocket Richard was the seed that started the quebecois movement
If there were no Richard riots Quebec would be majority English today
The muhammed Ali of hockey
Those first two things are not at all true. There is an Ali type element to Richard though where he is more folk hero than player, or at least had been at times, and a lot of stuff with both gets glossed over or exaggerated for effect.
Anyway, in general it is going to be players who had great numbers but did little else who rise, and players who did things that don't show up on the scoresheet who fall. Memories fade while numbers stay the same, and people are not interested in watching old games. Esposito always comes up and is overrated in these threads for the same reason. There are exceptions though.
Richard and Sawchuk are the most historically significant ones that come to mind for me. Richard was viewed as a legitimate rival to Howe for several decades, and Sawchuk was regarded as the consensus answer for best goaltender in history. Neither of those things is considered now. I think that most of us can grasp the reasons. Richard's legacy goes beyond hockey and is impacted by the way he acted as a symbol for millions of people, while Sawchuk had numbers that dwarfed those of his biggest competition plus a very highly regarded peak. Memories of Richard's cultural significance and Sawchuk's peak are pretty faded, and their records are long gone. Playoff heroics are also not going to play as well in the distant future because people mainly look at regular season stats and playoff statistics are much more context dependent than those from the regular season.
Lemieux and Jagr were both mentioned and they have both gone up for the mentioned reasons. Public opinion on Lemieux significantly improved after his first retirement by the time he came back. CEO Lemieux, the version of him after his comeback, always came across as the classy leader of the sport, the guy who showed up internationally, the legend everyone missed. A far cry from the fairly surly, sullen Lemieux that often came across in the media. Jag also had a significant improvement to his image during the latter stages of his career as people forgot about sullen Jagr and enjoyed goofy old man Jagr. Mogilny has come up and he is strangely overrated on here recently. This will continue for a while until a few years after he inevitably makes the hall of fame, after which he will go back to being viewed correctly as a very marginal hall of fame case.
I imagine someone like Ted Kennedy is a good answer for this thread. Elite two way player, not really an elite scorer, elite playoff performer before the trophy for being an elite playoff performer exists. Toronto fandom also really focuses on guys from the 1960s teams way more than it does on players from previous dynasties. Old player without a gimmick to hang their hat on are inevitably going to see their status fall as people forget them but Kennedy is probably more susceptible to this than most.
I predict that Toews will see public opinion change in two different ways at the same time. The media will not overrate him as much, but underrating Toews will eventually cease being such a misguided strategy for fans to seem smart and he will maybe settle into his proper place.