Frequent computer users do not feel comfortable replacing their laptops with tablets. They bring their laptops with them. And then they say, "Do I really want to tote around a tablet as well?" The answer is no, their tablets languish at home, and they don't upgrade.
Very casual computer users may largely or entirely replace their computers with tablets... but they're very casual users. They don't want to be on an upgrade treadmill, and their needs are modest. An old tablet works fine.
My tablet can't replace my laptop at all, but it's a great device for traveling, reading, and watching videos.
There's been 3 updates to the iPad mini since mine, and felt zero need to upgrade. I'm very happy with my ipad, and most certaintly don't think it's meh, it's just apart of my evening cycle that I don't even think about any more.
Whoever wanted an iPad pretty much got one already. That void is filled.
It's not selling as much as in the beginning, but of course, there are apps being bought, people get the new model (or have their iPad die on them - yep, saw it happen)
After his demise, from what it seems, Tim Cook never felt for the iPad the same way as Jobs did. Tim is far more profit-centered than Jobs, and Apple's performance numbers lately speak for it. Unlike Steve, Tim Cook doesn't seem like a visionary either. He doesn't appear to have that urge of bringing change into the world.
He isn't of the type who has ability to bring that element of movement into his products. I could be wrong but it seems so. For example, he is unable to see the difference between the idea of revolutionizing education space and the idea of letting out a fashion accessory that competes well with swiss watches!
I mean you get the point, right?
[1] http://www.imore.com/steve-jobs-ipad-freedom-porn
[2] http://allthingsd.com/20120705/the-7-inch-ipads-biggest-crit...
Take my mother-in-law (please) for example. She does _everything_ on her iPad. Banking, email, surfing the web. She literally (yes, literally) hasn't touched her desktop computer in years.
But, she's still only on an iPad 2. She'll run that into the ground before she'll get another. She loves it, but isn't on any "upgrade cycle", the same for many people.
Now, it would be different if iPad sales were down 18%, yet Android or Windows tablet sales were rising to fill in that gap. As it is, _all_ tablet sales are down.