In short, information regarding doctrine has become simplified in recent years
Simple doctrine for simple minds.
I'll address your larger point shortly, but I want to throw in an anecdote to illustrate my simple-minds point.
The other night I had dinner with a JW. I was waiting for her inside the restaurant at the bar. She called for me to go meet her outside. When I saw her she was looking ridiculous "smoking" a black and mild cigarette. It was obvious she wasn't inhaling it. I grabbed the cigarette from her, took a deep breath, and puffed it out. She understood what I was getting at, put the cigarette out and went inside.
We discussed a variety of topics over dinner. It was clear that, in addition to her "smoking" habit, she was leading a double life in other ways. She then got on the topic of religion and asked me if I missed the meetings. I told her I've never been happier in my life. She replied that she still "loved Jehovah" but had done too many bad things in her life to deserve his love. I told her that her depression was caused by the guilt she was carrying around. She then proceeded to attack me along the lines of "how could you forget everything you learned about Jehovah?" I told her Jehovah was a fairy tale, like Santa Clause or the Tooth Fairy.
My response clearly upset her. The following is a paraphrase of what followed:
"What about everything that's going on? The world is getting worse."
"No it's not. It's getting better. People are living longer, healthier lives than ever before. One-hundred years ago the average life span was much shorter."
"That's not true. People lived an average of 120 years back then. Life spans are getting shorter."
[Confused look on my face] "Stop being so negative. Think of how lucky you are. You were born in the richest country in the world [United States]. You could have just as easily been born in sub-Saharan Africa and starved to death as a toddler."
"You're wrong. The richest country in the world is Mexico. You don't know what you're talking about."
[Stunned expression on my face again] "Okay. I spent eight years in college and I somehow missed the fact that Mexico is the richest country in the world. That must explain why so many illegal immigrants leave the richest country in the world to come to our country every year. I'm sorry."
"Now you're just mocking me. I don't know why I'm arguing with you. You don't listen and you have no idea what you're talking about."
[Change of subject]
I wish I could say she's somehow an exception, but most of my conversations with JWs have revealed a shocking ignorance of the world in which they live. Critical thinking is pushed aside. Many of them just make up facts that support the Society's position. Granted, she is an example of a JW more on the ignorant side of the spectrum, but her example is typical, unfortunately.
Back to your larger point. The "simplification" of doctrine, if you will, follows the change in leaderships. Fred Franz filled in as the primary theologian for the religion for 30+ years. He had a high IQ with an equally vibrant imagination. After the GB coup of the early 70s, men were chosen for top leadership based on loyalty, not capacity, as confirmed by Ray Franz in COC. What has resulted in GB 2.0 is a bunch of brainwashed yes-men with an extreme loyalty to the core of JW doctrine, but who are not necessarily the most qualified to lead such a large religion.
Nobody on the GB appears to be capable of inheriting Freddy's mantle as chief theologian, so they're not bothering with that anymore. Why should they? Their membership doesn't require it of them. Those intelligent enough to see the doctrinal flaws have already left or have been purged. So long as they continue to recruit from the third world, they will post insignificant increases year after year to cover up the steady exit of your more independent-minded JWs.