I think they did it because the Buzzard method made those missions too easy.
Just like they patched that crate mission when you have to chase down 4 cars to see which one is holding your stuff.
Before you could just set your gps to special cargo and it would point out which car was holding, they removed that too.
Nothing has changed, has been like this since last December. You always had to make sure the target doesn't take cover next to the car. Mindlessly firing rockets always came with the chance of blowing up the car. Destroying the car on purpose has never been an issue. The quick GPS thing is a different story.