Why did they make those changes? Is it only because of the safety and cost constraints? Or could they have come closer to the concept (whie also meeting safety and cost constraints)?

The production car looks good, but the concept is really in another league. I wish they could have (or would have) kept the longer nose/tail, maintained the smother lines and made it wider (maybe even lower). It's a little too much charger-esque. But I'm looking forward to seeing it on the road. It's going to be a real competitor to the well-selling Mustang.