i don't necessary think the wrist down a flaw. i have seen karate raising block using the wrist and the same thing with various Chinese arts. it couldn't be bad, could it? isn't wrist down to send energy up and palm up to send energy down? but then, does it matter whether wrist is down or up? just thinking out loud.
*got to stop thinking altogether. talking about dangerous habit!*
It's not a flaw of Aikido Just our Aikido...