I sat in a state of meditation as a wizard using the armor and flat shield. I completed my meditation as one of the level 1 rogues stabbed me 15 times Dark And Darker Gold. I stood up and 1 shot him. What is "fair" or "fun". I was not able to kill him because I was on a square which he was unable to break with a dagger and my character was body blocking the way up. He literally had nothing but chest shots to hit. I was stabbed for 5 or 6 seconds. I was left with 70% health. A green health pot would have out his healing. But give them a blue short sword and they will 1 tap barbarians.
Outside of cheaters/netcode/etc that hard wired can be fixed with issues with release, damage scaling must be closer to defense-scale scaling. At present, damage scaling is exponential, quadratic, and inconsistent.
The health and armor of the player do not attain a level that is high enough to justify how much impact can be. This results in massive differences between basic classes.
Rogues and wizards are not able to take out mobs. Barbarians can 1-tap actual players. To large a gap.
A very good source of information here.
There is some definitely good incite here my friend. However, there are many things you may have missed. It's time to break this down into smaller chunks and debate particular topics. We will focus on my ideas as a whole that are based on wizard and rogue that you decide to focus on.
You've highlighted some aspects of the wizard that are factual. However, I also can tell you're not incredibly knowledgeable with the wizard. Chain lightning is more then than a viable. In a aoe perspective. It is only able to jump over X number of enemies. These enemies are closer each other than cheap Dark And Darker Gold. It isn't a problem for you. It is vary situational.