It's really weird that there is that restriction because all of the other 4G phones on Verizon can do simultaneous voice+data. Must be something weird about this new all-in-one qualcomm chip they are using.
This is SUCH a bummer. Honestly, I'm really happy with my iPhone 4. The one feature I was excited about was LTE and the promise that I'd get simultaneous voice and data on Verizon (I had an AT&T iPhone for years -- VZW service is vastly superior in Oregon). Now I'm seriously considering an Android device. If only I weren't so deep in the Apple ecosystem.
To be honest, that use case has rarely come up for me, if at all. I'd much rather have the confidence that I'll be able to make a call (something you have with Verizon, but not with AT&T).