I'm not defending Apple's decision by any means, but I think these concerns over 2GB of RAM are unjustified. How slow has Apple been to upgrade the RAM in their devices? I don't see them shifting all of these products to 4GB any time soon and developers are not going to abandon them.
Developers are still targetting 1GB devices like the Air, and 512MB devices like the iPad 2 (and lament the iPad 3). Some apps will benefit from the breathing room from 2GB (no, not a stock tracking app unless you are tracking tens of thousands or millions of stocks), and fewer still from 4GB. The bad news is that web browsers are the poster child of an app that will use unholy amounts of memory, and everyone uses them.