I didn't consider the memory problem but that was intentional.
It's hard enough to code a game, let alone, code it so that it can take advantage of motion controls.
If anything, the XBLA developers are given less freedom and with Nintendo's WiiWare service, they're given more room to move around, if you will.
Additionally, WiiWare is tapping into a much more diversified market than developers could using the XBLA.
There are many developers that have already commented that they enjoy working with Nintendo's WiiWare service much more than the XBLA for varying reasons.
I can see why.