I remember that talk about salvaging destroyed vehicles too, but still there should be a penalty for leaving a vehicle unattended. We should be able to either hack it and use it or deconstruct it for resources, I would include the Infiltrator besideds the Engineer. Blowing up unmanned vehicles is not what I would consider fun.
Hacking and deconstructing on the other hand I had lots of fun with in Planetside1 especially with people still inside, there is nothing like running somebody over with their own vehicle
.
Vehicle hacking and enemy weapon looting are my 2 biggest concerns about Planetside 2, it just would make it less fun for me.