iOS 8.0.2 doesn't fix the wifi sync issue. More likely, the hard reboot caused by the upgrade process is a temporary fix that eventually falls apart. Still waiting on a fix.
My iPhone 6 has been showing up in iTunes since I updated to 8.0.2 this morning. But I've gone 24+ hours previously and then seen it just disappear from iTunes.
I'll see what happens tomorrow, but I'm inclined to suspect that you're right. Whenever you see dozens of different "solutions" to a problem, some with multiple steps, and they all end with "restart your iPhone," I suspect the restart is the real, but temporary, solution.
I hope everyone who's experienced this minor annoyance has submitted feedback to Apple in some official way. I've used Feedback Assistant in Yosemite beta, and will do so again tomorrow if my iPhone falls off of iTunes' list.