I'll pitch in.
The way leveling is implemented in most modern MMOs (and by extension, most RPGs and JRPGs) makes no sense.
What's the point of leveling up if, at level 3, you're doing regular quests around town, fighting level 3 Crocodiles that take five seconds to kill, and then at level 113, you're doing regular quests around town, fighting level 113 that take 5 seconds to kill? Literally the only difference is that 1. the numbers are inflated and 2. you have more abilities, but ultimately it still takes you five seconds to kill the mob, and they are no more relatively dangerous as a level 113 mob to you then they were when you were fighting them at level 3. The only difference is that you are in the latest area.
If you're a level 113, and waltz back to that area with the level 3 Croc, you can one shot it. What's the difference between that level 3 Croc and the level 113 Croc?
Leveling is a great idea, but I'm rather suck of the arbitrary way it's implemented in modern games. Personally, I'd prefer a more linear powerlevel curve, or at least hold off on the exponential curve until the very final expansion or last legs of the story. A Croc in every zone and every expansion should have the same numbers. There should be no such thing as "level 3" Croc and a "level 113" Croc. There should only be "Crocs", and there are always level X. With a linear powerlevel curve, Crocs would be terrifying if you were a low level player and would take a group to kill. At high levels, you could solo the Croc, but they're not going to fall over and die in two hits, and you will still need to pay attention.
When the game goes on for long enough, the numbers just don't make any sense whatsoever. I remember towards the end of Mists of Pandaria, the powerlevel escalation became so insane that the mechanics stopped making sense. Players were dealing dozens of millions of damage per second, so bosses need billions of health. However, the servers would crash if bosses had more than 2.1 billion health (the largest value a 32 bit integer could hold was 2,147,483,647), so you started getting convoluted mechanics like the players almost killing Garrosh... and then he heals right back up. Four times in a row! So the devs had to implement something called a number squish. Then we were right back to ridiculous, server breaking numbers one expansion later, so they had to implement ANOTHER number squish. And now, we are right on track for a THIRD number squish! It makes no sense. How about... not trying to continuously build your game on an exponential powercurve? It's cool to see 7+ digit numbers, but please hold off until the VERY DEFINITE ENDING of your game or story.
Another gripe: faction systems. Goodness gracious! (This concerns factions which exist as a part of the developer driven story, not player created factions in sandbox PvP games). What ends up happening is that the owner of the IP begins building up the appeal of the game by emphasizing the factions. Being Horde/Alliance/Guardian/Defiant/Republic/Sith/Federation/Klingon/Exiles/Dominion/Order/Chaos then becomes a core part of the player's identity in the game. Players pour a huge amount of their investment in the game into the faction conflict storylines, which prevents the storytellers from doing any status quo changing storylines such as the destruction of a faction. It's the same problem tabletop war games have faced for decades: no one can win or lose because that'd eliminate a faction and thus eliminate the attachment people have to the game, which leads to story stagnation. I was really hoping that MoP would be the definitive end of the faction war storyline. I was hoping that they'd lift faction restrictions and allow Horde and Alliance to fight evil together. WoD got my hopes up with the two factions working together for once... but then Legion hit and Blizzard had to go back to the well of Horde vs Alliance nostalgia.