Please give an example of Vader's "depth" from A New Hope
His voice was deep as shit.
As for Kylo Ren, his story with Han, Lea and Luke is straight out of corporate America. It's like, imagine Luke, Han and Lea are now some industry bigwigs. They all went to college together. Luke and Lea had a thing but it didn't work out, but the three of them are real tight. Lots of long nights studying and working on pet projects until finally they stumble on something great and drop out of college to fight hard to bring the product to market. Decades later they are the legends that most start ups dream about, riding high with equity coming out of their ears.
They have since settled down. Han marries Lea and they had a kid; Who has now just finished college and is being groomed to take his place in the pantheon of business gods. Except, something goes wrong. The kid is a total nightmare; an over protected, over privileged, entitled spoiled brat. Han and Lea are worried but they hope some ownership in his work will smooth things out. Once he gets his first project under his belt he will be hooked.
So he comes on board and starts working in a team headed by Luke on a special new project. This thing is going to be big. That's when stuff goes down fast. Kylo flips his shit over having to obey people who he doesn't even know, and hates the workload and responsibility. So he winds up doing the unthinkable, he goes rogue and steals the info on the new project and sells it to the competition. There is a scandal. The media rips the family business apart, investors start bailing thinking this is the sign that they have simply aged out of the market and are no longer relevant.
Han goes into early retirement; Luke goes awol on some sort of spirit quest in the Himalayas and Lea is left trying to manage what's left of the enterprise after a massive round of layoffs. And then there is Kylo, smiling at his brand new shiny top floor office suite at Backstabber Inc.
That's pretty much the backstory going into TFA. They wrote it to resonate with every parent who has ever been disappointed with their talented but spoiled and morally deficient children.