Negative impact of slow speed traveling is that locations are players free. There were times you were able to find many players at outside zones, but now? Players dont visit that locations, because it takes too long time, or they have cars and they dont need to stay there after they finished witht their tasks.
I would like to see implemented principle of "travel and stay (for a while)". I.e. at second week in a game month, every stuff selled by NPC traders are one half cheaper, ... or more spawning drugs in trader...
You would have a reason to stay in distant locations, but to maximize your effort, you need to stay there for some time. People would communicate among each other, .. .
Idea about Hinkley. Hinkley is good place to visit, fight, chat.. but it is shame that it is near HUB and there is not any relation with this city. So you would be able to "cheat" in Hinkley (one free stimpack or avenger or drug, ...), but you would need to solve some quest in HUB, that would grant you temporary this benefit (after this, you would need to repeat this quest). ...
I hope you understand me.