No, it really wasn't. Did he have some idea the 4S was the direction it would take? Sure. But for God's sake, that phone was released a week and a half after he died. He hadn't been at work very much for a year before that.
The 5's screen form factor hasn't been taken advantage of at all, the new enclosure, while nice, you literally cannot call innovative, LTE isn't innovative, it would've been 4 years ago but last year it was old news. And the lightning connector isn't innovative in a world where it's getting clocked hard by USB 3.0, which was a done-deal standard by the time Lightning was announced.
The 4S, while having a better camera, it wasn't a huge jump, and Siri was software they removed(which had more features) from the 4's app store.
The 4 was the last truly innovative iPhone- no one was talking screen density, and they nailed it. The new camera was a gigantic step up, the front facing camera was as well.
Also, you missed with the iPhone->3G that the App Store came into existence.
As to the iPad, the iPad 2 was commonly referred to the moment it came out as "The iPad that Apple meant to release." because of all of the small, but numerous, improvements. Adding Retina to the 3 is arguably a similar jump, though admittedly I don't have a lot of room to really know, as I don't own one.
iPhone -> iPhone 3G: Addition of 3G, GPS. enclosure became plastic.
iPhone 3G -> iPhone 3GS: Video camera
iPhone 3G -> iPhone 4: Retina, significantly improved camera, new enclosure, addition of front facing camera
iPhone 4 -> iPhone 4S: Siri, better camera
iPhone 4S -> iPhone 5: New screen form factor, significantly improved enclosure, lightning connector, LTE
iPad -> iPad 2: thinner and lighter, cameras
iPad 2 -> iPad 3: LTE, Retina
iPad 3 -> iPad 4: lightning connector
I don't see any significant decline in diff quality over time.
edited for correctness