I agree, Fallout 3 at least had random encounters. And trying to see all of them could be take some time and multiple playthroughs. Plus, the free roaming in my opinion...was done properly. You didn't have to worry to much about going to a certain spot and bumping into really tough creatures or fiends who are pretty tough when fought at the early levels.
And the locations weren't very interesting, neither was the terrain. I was expecting to explore more of Red Rock Canyon, or even more of the mountains by Jacobstown. I found that good chunks of the map in NV are unreachable. Around Jacobstown, Nellis AFB, "The Divide", and the so called "Deathclaw Promontory" which just had some loot and a lot of deathclaws. It was a nice unmarked spot, but nothing worth doing more than once. That and a lot of places seemed useless. A lot of the spots around The Strip were empty or lacking people.
There weren't any interesting settlements like Megaton or Rivet City. And most of the city of New Vegas is empty compared to the ruins of DC being full of muties and BoS dukeing it out. Plus, there were a lot of buildings to explore and loot to grab and XP to get. I find only a few locations have good loot, most are full of junk and just about all are small and don't have much
I will say New Vegas has more quests, but most of them either align you with a faction or require a faction alignment to take.
Both are great games, I like how New Vegas kept true to the first games. But I think they need to adapt it to fit the new formula Fallout 3 created.