In all three of your examples the user reviews were skewed by protest votes making the user reviews less useful than the critic score - not the other way around as you seem to be assuming? This is common on metacritic where DRM is involved. If the game has DRM, then unless you're the kind of person that refuses to play a game, no matter how good it is, if it contains DRM - then you can't assume the user reviews are more accurate than the critic ones.
For your example games:
Diablo 3's user score is aimed by the users at 3.7 in reference to 'error 37' experienced by players shortly after release and in no way actually reflects the user opinion of the game.
Mass Effect 3's was a protest vote against the end of the game rather than the game as a whole.
Most of the SimCity votes were based on the fact the game effectively didn't work for 3 days after release rather than an opinion of the game.
That's blatantly false. Yes, some people negatively reviewed Diablo 3 because of launch issues, but regardless of launch issues the game was extremely flawed at its core. Launch issues didn't stop people from playing the game shortly after they started... Repetitive maps, horribly implemented itemization, a huge difficulty increase in Inferno combined with this lovely new "feature" called the real life auction house did. You could play for a hundred hours and not find an upgrade for your character, but you could pay $250 and get it on the auction house! The game was broken and was pushing people towards spending real life money to be able to progress in a game they already paid for. On top of that, Blizzard had no problems "nerfing" stats that people paid real life money for. You can see how that might upset people.... Yet, the horrible itemization, huge increase in difficulty and a practically forced push towards the real life auction house was absent from almost every professional review. The game's problems went well beyond launch issues because if the only problem were launch issues, people would've gotten over it and played the game when the launch issues cleared up. The problem is after the launch issues, when you do get to play it, is when you finally get to discover how broken the game actually is.
The exact same was true in Sim City as well. The entire Residential, Commercial, Industrial aspect of the game is completely broken. Literally, broken and that's the core of the game and that's practically never even mentioned in a professional review. The extremely small size of land you have to build on, the completely useless AI that always goes to the nearest house, nearest job and leads to giant traffic congestion almost all the time. Game-breaking bugs that can't be fixed and force you to restart when they occur in your city. Multiplayer "features" that don't sync properly, and just flat out don't work. Phantom sims added to make your city appear bigger then it is and since your city has to be saved online, constanty city roll-backs that cause you to lose everything you've done, through no fault of your own.
These games were deeply flawed, well beyond launch issues and should've deserved far lower scores even if they both had perfect launches. To sit here and say these games only have low scores based on launch issues is blatantly false. Sim City deserves a 20 rating because it's flat out broken at its core, not because of launch issues. I also disagree that users should have to update their scores. The reviews were accurate at the time they were written. If games don't want to be bombarded with horrible reviews, then don't release games that are clearly not finished and not ready to be released. I'm sure Diablo 3 is far better now than when I reviewed it, but that doesn't negate the fact that the game was broken when they released it and I haven't replayed it since nor is it my responsibility to replay it, and update people with the changes they've made. People interested in the game can read the problems that existed, and do research into whether or not those problems have been fixed and if it ends up in someone not purchasing the game, that's not my problem.