While I'm not disagreeing with your premise that Vonleh shouldn't be given a lot of run at the 3, I don't his think handles, or relative lack thereof -- especially relative to two of the biggest superstars of this generation -- is sufficient argument to support that. Guys like Wes Matthews and Tony Allen have obviously been extremely successful without great handle.
As to Vonleh as a 3 in general, I don't think it should be a full-time idea, but can see a couple scenarios where it might make sense in short stints:
- going big offensively with Meyers stretching the court as the 4
- going big defensively against Lebron