I think it comes down to risk assessment & mitigation planning. What situations would cause me to bug out? Where would I be bugging out to? What weather conditions do I need to plan for? What possible routes will take me from my starting point(s) to my bug out location(s)?

When you can answer these things, the question then is do any of these potential bug out scenarios require a 4x4 vehicle? I'd also add in there, do I have the skills & knowledge to take advantage of 4x4 capabilities.

When I ask myself these questions, I don't see the need for a full-on 4x4 vehicle. It might be nice to have more capability than I think I need, but I don't think its really required.