There is a certain subset of the population, for whom power is everything. It's better than sex, it's better than money, it's better than drugs, it is the end-all and be-all number one thing that givest them satisfaction.
Some of those people wind up as politicians, others wnd up as CEOs, and others gravitate toward religion.
The Governing Body of JWs is full of them.
Imagine that you are like them, that the feeling of power, of control of absolute authority is the only thing that comes even close to making you happy.
Now imagine you are on the GB. In your everyday existence, strolling the halls of Bethel, you are met with deference, people immediately stop what they are doing when you approach because, clearly, whatever you say or request takes precedence.
You get to travel to far off lands to give assembly talks or dedication talks, or just "visit the troops" in a branch. You travel first class, you stay in first class accomodations, you eat like a gourmet, all without having to dirty your hands touching that filthy cash - you get the best of everything without ever worrying about money, just like Bill Gates or Steve Jobs or Prince Charles.
While there, you give a talk in front of, what? 10,000? 50,000? Maybe 100,000? Before you say one word, you get a thunderous ovation. They hang on your every word like it's coming from the mouth of Moses himself. When you are done, more clapping & cheering. Afterward, people line up for hours just to have the honor & privilege of taking a photo of you, touching your hand, stammering out a few star-struck words, and maybe slipping an envelope bulging with money into your hand.
All the while, for all or nearly all of your entire life, you've come to believe that out of 7 billion people on earth, God talks to just a dozen or so people at any one time. And right now, you are one of them! You have a direct pipeline to God. He sends his holy spirit to talk directly to you, like (almost) no one else on earth. That sudden flash of insight, that new thought you just had? That wasn't just a synapse in your brain making a new connection - no that was HOLY FREAKIN' SPIRIT shooting down the express lane from HEAVEN ITSELF right to YOU.
And that authority complex gets filtered down the pipeline. Branch overseers have a lot of it, but a little less than a GBer. DOs have just a smidgen less, COs just a tad less than that, and so on.
A lot of elders have this need for authority as well. They aren't competent enough to rise up thru the organization, but they want to tap into that authority vibe anyway. In "real life", they are only a small business owner, or a cubicle worker, or a used car salesman, but on Sundays & Thursdays, boy, watch out, 'cause they have the power and authority now! They may suck at family life, they may be emotionally stunted, they may not earn enough to buy a 10 year old car, but by God, they've been successful at the Kingdom Hall!
And heaven help the mere "publisher" who would stand up to them, who would threaten to take that little sliver of power and happiness away from them.
THAT's why there is an "authority complex" in the organization.