I agree with you that Apple could not really have feasibly avoided releasing iOS4 on the 3G/3GS, but the author makes a fair point that they do own the whole stack, and either didn't test performance or didn't care enough to tell people that it would perform slower on older hardware. It's not like iOS 4 on 3GS hardware was an unforeseen combination. From what I've seen from friends and on Youtube, the problem isn't minute, either - it's a drastically worse experience. It seems like something like that should have been caught.

I don't have iPhone 4, and can't say much how is the performance. But according to my experience, it's software issue (memory management). After upgrading my 3GS to iOS, my daily task is to kill all apps in the multitasking bar when it feel sluggish. I can check from iMemGraph, the free memory is increased substantially.

And I'm sure these same people are also complaining about the lack of iOS 4 support on the original iPhone. These same people probably also complained about lack of video recording in the iPhone 3G. In all cases, jailbroken phones have shown that these features simply don't perform on the lower end models.

It seemed like the original author spent an unseemly amount of time complaining about the performance of the iPhone 3G when running iOS 3 and iOS 4. Not to defend Apple, but before the iPhone, you had to buy an entirely new phone in order to get the latest OS. I think it's incredibly impressive that I can "upgrade" the iOS on my phone to a new whole number release. Twice! Even if it doesn't, my phone isn't gonna magically stop working because iPhone 5 or 6 comes out. I don't HAVE to buy a new iPhone just because Apple calls it magical.