@Arkandel I totally get what you and @ZombieGenesis are saying here; I even agree to an extent. My opinion is just that no matter what system is used, someone is going to come along and abuse the Hell out of it, because that's their thing. Not necessarily doing it so that they have a massive advantage over others, but because of the challenge of the build. Even if it doesn't make logical sense, it's a challenge that they engage in, a puzzle to solve. There's a thread on an M&M Facebook page right now about 'how to build Gambit at PL 5'. Most of us are going '....Why?', but that's the challenge and attraction for that player; how to build a character he enjoys with sub-optimal limitations placed on it.
I also get what you're saying about 'wasting plot'. But, strictly my own opinion, comics and superheroes aren't as 'plug and play' for plots in the same way, say, a fantasy RPG or science-fiction RPG, or WoD. Comics & Superhero plots are not solely defined by their scale/power level, but by the villain behind the plot, and Supervillains tend to stick to one hero or group the majority of the time. The Fantastic Four go up against Dr. Doom all the time because of that initial point of contact between Reed and Victor in college, which has blossomed into rivalry. There's no logical reason why the Avengers don't square off against Doom and his latest plan to conquer Earth/the Universe/Whatever, but there's not as much tension, history, and connection there, so it's a rare occurrence. Same with Magneto & the X-Men. Even after Scarlet Witch and Quicksilver were in the Avengers and discovered he's their father, Magneto is mostly the X-Men's foe to deal with. In other games, you can have personal vendettas between protagonist & antagonist, sure. But mostly, you have a generalized situation with an all-purpose Antagonist/Villain/Challenge because you don't know which players are showing up to the Event.
And, again IMO, this is another point in the favor of an OC's super game over an FC game: no established relationships going back decades of comics history, either between protagonists or between a protagonist & antagonist. It's a clean slate. So, your Dr. Doom expy can be a full-on global threat fought by whatever hero group happens to be on hand. Your metahuman supremacist is fair game for any group to foil, rather than just one particular group of metahumans trying to show a positive front to humanity that they're not all threats and would-be conquerors.
In regards to disparate levels of power being more lethal to less 'experienced' characters, that's true. But, nowhere does it say that the less-powerful characters are required to square off against the Big Bad directly. Time and again, the Justice League face Darkseid. Batman is completely outgunned by a character who is more powerful than the team's heavy hitters of Superman and Wonder Woman. But, Batman still either wins, or contributes to the group win. He takes down Paradeamons that are slightly more powerful than him but still manageable so that the big guns aren't swarmed while concentrating on Darkseid. He feints and uses attacks that have no chance of damaging Darkseid, but open him up to other attacks from teammates that can do real damage. He stealths off and attaches explosives to Darkseid's stockpile of planet-destroying artillery, then threatens Darkseid into ending the fight and giving up, or having Apokalypse blown to atoms.
In other words, Batman's player knows his character's limitations in a fight and figures out how to contribute accordingly.
The same goes in the opposite direction: the hero that's way overpowered for the situation/event. GM's/Event runners can use distractions to prevent the Kryptonian from wrapping up a scene in a single round. Superman or Thor shows up to stop a bank robbery; gang leader says something to the effect of 'Boss thought you'd show up. So we took precautions..' then activates a series of explosions on a bridge, forcing the OP character to save lives instead of bust some easy skulls. A stray blast sets off an explosion and the OP character has to concentrate on rescues & evacuations & crisis management while the others fight. Or, the 'precaution' that the bank robbers take is a more appropriate powered thug/villain (like Rhino) bursting out of a nearby van they were waiting in just in case Superman/Thor tried to stop the robbery; the OP character now has an appropriate challenge to be focused on while the others deal with the robbers and maybe help with the new bruiser. Is it as satisfying? Depends on the player. When I've played Kryptonians on freeform games, I've voluntarily taken my character out of the battle by these methods so that the other heroes in the event/scene get equal time to shine.