For me, it was how the announcements were made, they did seem to just feel like they had a massive "Wow" factor.
Even way back on the first iPhone announcement - When Steve was on stage and talking about the Palm and Blackberry devices having "physical keyboards", and that he had merged it all with the iPod with touch screens, to me that seemed like a massive jump. (OK I admit, at the time I was very much in the camp of "my Blackberry's keyboard is the finest!", but I watch the announcement back again... there was a very Steve Jobs finesse to the whole thing!).
The more recent announcements have kinda been a bit "meh", and I think maybe it's just that - I think a new type of device that has not been thought about, would bring back the "Wow" factor again.
I think, just for me anyway, that jumping over the releases (so skip a release and upgrade), I see more of a jump, than say if I was going between each version.
Anyway, my thoughts - and I don't know - maybe others see the same with the announcements not quite as they used to be - due to the slowness of "upgrades" to the product.