Backpack would be a nice idea. I suppose one way for them to work would be if the player had an absolute limit on their carrying capacity (depending on strength), and the backpack lifted that limit.
So, without a backpack you could run up to a certain weight and then jog after that, before reaching a point where you're told "You can't carry any more" when you try to pick up extra stuff. With a backpack, instead of being told you can't carry any more, you can carry as much as you like but you're reduced to walking.
Um. Did anyone ever suffer the 'can only walk' penalty that came with carrying too much? Would they? Or would everyone just say "If I can't run I ain't carrying"?
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As for vehicles, apart from having been confirmed not in (apart from the rideable vertibird as seen in the trailer)... well, the game will have been designed to get everywhere by walking, and Bethesda will have tuned the density of content accordingly. If a ground vehicle is fast enough to be exciting, it'll be too fast for the way the game is designed.
At best you'd hurtle along, detecting huge numbers of interesting places but never having time to investigate them, until you had a map full of clutter. That would be great for completionists, who might be happy to have lots of places mapped out to visit once they've completed the main quest. Not so good for immersionists.
At worst, you'd hurtle along triggering lots of random encounters and location-triggered quests, and then rushing off without even noticing them. At worst worst, you'd pull up at your home, go to sleep for a couple of hours, and upon waking up be attacked by three assassins who'd tracked you across the wasteland, while a bunch of other people urgently tried to engage you in conversation about their lost Protectron, kidnapped husband or sick child .
I reckon the only vehicle that would work in the game as Bethesda designed it to be played, would be something fairly slow. As suggested in another thread, something rather faster than running, with a trailer that you could load with trade goods.
Or maybe a flying vehicle, depending on how Bethesda have implemented the vertibirds.
Of course, with mods we'd have the option of using vehicles that let us play the game as Bethesda never intended - and on our own heads be it !