Quick Nexus S Jelly Bean/4.2 vs iPhone 4 iOS 6 question

I have an iPhone 4, and it was released around the same time as the Nexus S, which is why I chose this comparison:

The Nexus S with the OS update gets to use photostream / google now, correct?

which leads me to:

why don't iphone 4 users who upgrade get the use of panoramic photos or siri? I'm sure this has been asked, and im also sure 'there's an app for that' (photostream anyway), but did they choose not to include them because 'the hardware isn't good enough' (which is what I've heard) or because they just want you to buy a 5?

(this is my first iphone - had windows phones since launch prior to this. also have a nexus 7 now and that is my first android device. i'm a heavy computer user, 80% windows, 19.871% some flavor of Linux, 0.129% mac)

certainly any camera can take panoramic photos, they just won't look as good. My iphone is great, but the way google now works and the little that I've played with on{x}, the next nexus is starting to look pretty sweet to me.

- I think it only bothers me because every time you look up iOS 6 features/tips/trick you get a bunch of videos talking about new siri and the camera. At least siri is on multiple devices, but the panoramic photos only work on the 5 if i'm not mistaken, making it a hardware feature.