The game is filled with fetch/deliver quests that are saved by strong writing. I'm on my second playthrough and I actually can't bring myself to do Return to Sender or the Still in the Dark quests again. They're too boring.
In the case of Return to Sender I agree to some extent. Imo, on a first playthrough the quest is great. Most of the quest itself is a mundane fed/ex (though it ends on a high note), yes, but it´s laid out in a way which pushes player towards exploration so he´s very likely to discover more points of interest in the process. Quite a few quests are designed this way and while I think it works great for the first playthrough, I can see how it can become a bit bothersome on subsequent ones, because this positive externality may become largely lost, especially if player has already explored everything on the first run.
I think that by then, it´s probably better not to concentrate on these too much and complete them in a more incidental manner.
In regards to Still in the Dark, I have to disagree though. First, there are many ways to obtain this quest, second, most of the locations you´re sent in contain their own quests and other quests lead to them as well. This leads, imo of course, to enough permutations to make completing the quest interesting enough even on replays.
The way quests incidentally lead to more quests or intertwine/cross with each other is imo one of the game´s main strengths, even though in its current state it´s not always absolutely airtight and sometimes can lead to bugged situations.
Also, personally I´d prefer the later game branching in the main quest to be cut more radically, I tried to play for all sides as long as possible and it did become a bit wonky towards the end.
I have to reluctantly agree that proportionately there is maybe a bit too much of the "travel across the map" simple fed/ex quests and it would be nice to have more quests completable mostly in one location, especially since most of these which are in the game boast good to brilliant quest design.
However, I don´t consider this shortcoming to be dramatic enough to pull New Vegas out of the great game category, because good amount of quite complex quests sporting multiple solutions, outcomes, taking sides and good writing, plus the above mentioned interconnectedness more than make up for it.