I don't think the "launched the wrong app" is really that uncommon a use case. And after launching the wrong app and already being annoyed, the last thing I want is my phone to say "screw you" and make it harder for me to get to the app I intended.
There's also the use case where you have a related apps on the same screen or in the same folder. If you open a Facebook app, how likely is it that you'll want to check out Twitter next? If you get done checking the NYT headlines, might you want to open CNN or Flipboard next? Sick of Angry Birds so you open up Words With Friends? These scenarios don't seem that unlikely to me, but the "go to screen 1" behavior breaks them.
I might be in the minority, but none of these are things I do. I never need to check Twitter and Facebook at the same time, or play two games right after each other, or open several news apps. If I have a few minutes to waste, I open one of these apps. If I have a lot of time to waste, I open Instapaper or the Kindle app or a game I can play for a long time.
Even so, presumably, if these apps are important to you and you open them regularly, you have them on the first or second screen, so making the home button take you to the first screen doesn't seem like a huge additional burden.
There's also the use case where you have a related apps on the same screen or in the same folder. If you open a Facebook app, how likely is it that you'll want to check out Twitter next? If you get done checking the NYT headlines, might you want to open CNN or Flipboard next? Sick of Angry Birds so you open up Words With Friends? These scenarios don't seem that unlikely to me, but the "go to screen 1" behavior breaks them.