I wondered about that as well. It was horrible on the iPad 2 Mini Retina... Made browsing feel like I was on a cheap 5 year old smartphone.
Why does Apple cheap out on the RAM? What is 1GB of RAM these days, bought in bulk? $1? Less?
I just don't get why Apple always puts barely enough in their devices. Only reason I can think of is that they do it for "planned obsolescence"... They want you to buy the next gen device, and so they make sure that whatever one you have is barely adequate for the current OS, and when the new OS comes out(that is barely difference than the one you have that looks like it did in 2007), that your device will slow down more and you will feel the need to upgrade.
Sneaky, I don't like that. RAM is CHEAP... For a premium device, splurge a little, Apple...