Do you honestly not know what people are talking about when they talk about having to buy the next generation of a device?
With every new generation of product, Apple introduces a new hardware element... it isn't just software.
There are people who want the full experience of Apple's products. That necessitates upgrading the hardware every time Apple produces another generation. Of course one could argue that wanting that is THEIR problem.
Technology more than just OS updates.
Problem with this, for Apple and others is that unless you come up with new ideas, and lets be honest, Apple is not the best on this point, Sales start to stall.
If you have a great idea, iPad, and just do pretty much nothing to it fundamentally since the day you launched it, after 5 years? you are almost grasping at weaker and weaker tiny changes you can make to it, to TRY and home people will want to upgrade.
Apple COULD have a nice wide range of tablets on the market now, and be totally and utterly dominant in this sector.
They could have for example, Video/Entertainment focussed models, widescreen, stereo speakers.
Larger/Smaller screens
They could have productivity models, USB and SD ports, detachable keyboards and pens.
They could have OSX based models.
Waterproof models for outside use.
I'm just thinking up concepts, but that COULD be the world, and an iPad for everyone. Different models, different styles different budgets.
Instead after 5 years we have basically the same dam model as they launched on day 1.
finer detailed screen, faster, thinner and a camera. That the totally amount of 5 years of invention for the worlds best? hardware company.
For me anyway, that's sad
If you had asked me, 5 years ago, day 1 of iPad what there would be in 5 years time, I would of hoped for more than iPad Air 2.