I'm definitely not arguing that they shouldn't have put 2GB in. It's been 3 years since they put 1GB in, and with the demanding resources of iOS 7-8, it was long overdue.
However, that's not the issue though. Even if Apple put 2GB of memory in the 6, you would still eventually run into the same situation when you have a lot of things going on. Apple doesn't know whether you want to save state to the hard drive or not, they can't make the decision for the developers because they don't know what needs to be saved. That said, it's so easy to save and restore state, it's one of the things you learn about in Apple's documentation: what to do when your app has gone into the background. App developers don't HAVE to save state to the hard drive, but a good developer is always mindful of what happens in low memory situations.
Again, iOS does *not* SAVE STATE. It does not use a backing store (ie, the disk) like OS X does.