For ME2 you spent a lot of time outside of council space, and also got a lot of benefit of the doubt and free reign from your actions in ME1. From the highest levels. Really it was because you were a player in a video game, but I felt that was a meaningful narrative justification that held up.
By ME3 they really leaned into it how Commander Shepard was in real time becoming a mythologized figure in the ME universe. And I think that is going to be a big part of the plot for this next ME game.
Apotheosis (as in the mythologizing of a real person, not actual ascension to real godhood) has always been a theme I have found interesting, but it isn't that common a theme is most forms of media. Seeing if they do anything with that theme is one of the reasons I am interested in seeing what they do with the next ME.
I feel the exact opposite. Mythologizing the player character destroys my SoD and I consider it a cancer on storytelling in general. I want believable down-to-earth stories, not more cookie-cutter "superhero saving teh universe" for the gazillionth time. It's narcissistic as hell and I get enough of that from social media.
That's not what I'm talking about at all.
Players being over the top larger than life action heroes has to do with action games wanting players to do over the top larger than life action stuff in the video game. It works with some games, it doesn't work so well with others. But that is not what I am talking about or what interests me.
I am talking about the process in a society where individuals are elevated to a mythological status. Often to the point of being deified. It can happen organically, with folk heroes and such, but also can be deliberate efforts by governments or those in power. It could be to increase the authority and popularity of political figures, such as why some of the Roman Emperors claimed godhood or the Kim family in North Korea, or it could be to create a unifying figure to try to help unify society in troubling times or to publicly elevate certain values. War heroes are often be mythologized for that purpose.
What is interesting is that mythologizing is almost never accurate. Whether by not including negative or derogatory details, by exaggeration, or by making up events that never occurred at all. That gap between the myth and reality, and why it exists, is something I find interesting.
The process of how a person who is relatively normal (although in most video games the protagonist is extremely abnormal to the point of it being very unrealistic, as you note) become a mythologized figure and how that impacts society and them, if they do happen to still be alive.
Shepard was just such a mythologized figure by the end of Mass Effect 3. It has already been hinted that Shepard's legacy, and possibly the character himself, will be an important part of the next Mass Effect. And exploring how his mythologization has impacted society and how it is used hundreds of years later has some room to explore some interesting ideas.
It could be badly done, for example:
Imagine them going full Church of the Children of the Atom except with Shepard, as preach by Pontiff Verner I.
Would be a quite dumb take on it, and I don't expect that is anything Bioware would do. But any idea or concept can be badly done.
More interesting takes would be how groups and individuals in the Mass Effect universe may try to claim Shepard's legacy to further their own agendas, especially as some of those individuals may be those that actually associated with him to bolster their claims. And also how they have chosen to shape the mythology and legacy of Shepard over the years, probably with competing mythologies that don't agree with each other. Especially since the player would have the perspective of being aware of the truth of those events to compare to whatever distortions there are in the mythologized version.
So I am curious to see if Bioware does anything interesting with that or not.