Like Steve Jobs never had his share of missteps either.
I would argue it's all a matter of perspective. Where you see missteps by Tim Cook (implying some degree of gross incompetence), I feel it's simply growing pains by Apple. They want to grow the Apple ecosystem in a certain manner, can't show every product the same amount of love, and so some sacrifices invariably have to be made. You simply didn't like the compromises Apple has had to make so far, but that doesn't make Apple wrong for having made them.
I am not saying Tim Cook is perfect, but I do like his track record. I doubt there are many other people who can match his accomplishments, much less top them.
The problem I have is that the Apple ecosystem really isn't special anymore. I tend to agree with your overall assessment, but I also see them losing their lead. This is somewhat inevitable. No one stays the leader forever. But the past few years have been very disappointing, especially on the Mac front.
They are neglecting what made them special in the first place, the Mac, choosing instead to put most of their focus on becoming a consumer electronics giant. Unfortunately their offerings in that space aren't significantly better than the competition. The iPhone remains the best smartphone but each year sees the competition gain. When it comes to services, Apple offers nothing unique or special. iCloud features are largely available via a variety of other services. There are numerous music and video services out there. Etc.
I don't think we've reached the post-PC era. I don't think iOS tablets are going to replace laptops. If anything, Microsoft has the right idea with the Surface Book. Jobs said it himself. The computer is a truck and we'll always need trucks. But Cook's Apple doesn't seem to recognize that, focusing way too much attention on trying to make wearables happen instead of delivering amazing Mac hardware at a competitive price point.
I cringe at how lame the Mac has become compared to the Surface Studio. I was completely blown away by that machine. Touch works perfectly well on the desktop. Phil is completely full of ****. But it's not just about touch on the desktop with the Surface Studio. Microsoft re-imaged the desktop computer and created a variety of interchangeable ways of interacting with it. The user can touch the screen or use a mouse. He or she can grab the pen and write on the screen as needed or place the dial on the screen and interact that way. It's not either/or. I can hold the pen in one hand and rotate the dial with the other. It feels extremely fluid and natural and, frankly, exciting.
Cook has done a great job of riding the wave Jobs built. But that wave is cresting. Other smartphones are reaching iPhone level of polish. The Apple Watch continues to limp along but has failed to become a "must have" device. The Mac is being neglected. And Microsoft of all companies has just released a line of computer hardware that completely bests Apple in terms of design and creativity. I also have no doubt that Microsoft is working on another phone concept and if the Surface line is any indication, I think their next stab at mobile will be truly competitive.