My input on the exploration in FO3.
There were more dungeons, no doubt about that, but there were too many and the things you found in them became mundane instead of being actual rewards for completing them.
While some had great design and pretty nice touches they just felt pointless to me and there were so many that they just started to feel repetitive.
In NV there are less dungeons and most can be very short, like the one by RRC where there are fire geckos, it's not big, 3 rooms maybe, but that's nice to me.
Why should it be enormous?
With the smaller size you could get a hang of what the dungeon was about and get done with it in a reasonable time.
While in FO3 a dungeon felt like it never ended a lot of times.
Some consider that a good thing, for me it's just irritating, the longer the dungeon the higher the challenge and the better the reward.
This was not the case with FO3's dungeons most of the time.
You go on for a loooong dungeon shooting moderate or easy enemies over and over and get maybe a skill book and some ammo.
While that fire gecko cave in NV was only 3 rooms big it gave a nice little dufflebag as a reward, felt quick, nice and I got a little something something for it.
Nothing great but neither did I in FO3's over sized dungeons.
And with the whole "shacks" argument; Why should there be a dungeon every 50 meters?
I like a gameworld that feels coherent, and while you most of the time get crap from these places it means that when you finally get something you feel a greater sense of reward for it.
In FO3 every place tried to have the player be rewarded for the dungeons and it just made the rewards mundane and cut down in importance.
So shacks might not be as interesting as the capitol in FO3 or the yao guai cave but at least it feels realistic.
I wouldn't say NV is bad because of it. (exploration wise)
I'd blame it on FO3 trying to force feed us with crap every single minute of playtime.
/opinion.