Kinda skimmed so if someone already said this oopsy. Mindflayers and other creatures used to get monster levels to show how strong they were compared to the basic races. This went with several of the races in 5e that are common now but, were actually basic creatures in previous editions. Tieflings & drow off the top of my head are good examples, they wouldn't get a class for several levels to counter how beefy the race was.
class system has always been d&d, off the top of my head world of darkness had a point buy system i think, there was also rift. That's to say were going to by pen and paper which is what d&d is based off of.
classes are archetypes, they aren't the rule of the game.
they create new classes any time they want. why not let me create a new class. exactly like i said. and build my new class with a point-buy system. if you want to play a classic barbarian wizard ranger sorcerer whatever, you should be able to if you want, you should be able to play a custom class if you want.
