RAM needs to be kept in perspective. This is not a Windows on X86 device.
The CC Pandora had 256MB. Yes, 1/4 of 1GB. It ran an entire Linux OS and can run about 90%+ of the Linux programs in existence.
The 1Ghz Pandora had 512MB. 1/2 of 1GB. So far I am not aware of any game, program or software that can be compiled for ARM that fit into the processor's capacity that was RAM restricted. I.e. the RAM wasn't preventing execution.
If the Pyra has 2GB of RAM, there is only one known scenario where that might not be enough: X86 virtual machines. Note, this is not the same as running DosBox or Exagear, but an X86 virtual machine would be expected to load and run one or more entire X86 Linux or Windows or other OS in a self contained processing space. For that, 4GB or 8GB would be beneficial.
The more RAM it has, the more it costs AND the more power it consumes. To go to 4GB might only cost $50 more for the chips, but that would be $50 more per unit for everyone - and 95%+ of people are not going to use more than 2GB.
I'm betting that some day, toward the last quarter of it's product life cycle, a "Maxed out" Pyra might get made. Much like the 1Ghz Pandora, it would use the maximum possible configuration available with the then existing hardware. We're 4+ years from that scenario though.