There is a completely different feel to it if it's an actual part of the game. I have had to resort to such 'self-challenging' for personal satisfaction. But if a game catered to such wishes, it would make the game feel that much more realistic. And again, considering the amount of MMORPG players that play specifically to hoard wealth/levels and the such, why not cater to their needs. Or the massive competitive playerbase out there. Why not make the game feel more 'real' to them with such a feature.
Yes, you are right in that features take time from the game developers. However, as previously mentioned, this does not have to be released together with the main, core game at its release date. That's one. And two, this would, again, give many other players 1) more reasons to play the game 2) make the game feel as of a higher quality and more enjoyable, having catered to their specific needs (competitive/or achievers).
If such a feature won't be added in, I'll simply have to find a way to delete the console out of F4, and restrict myself to one save game, of course. However, that would take away from the sandbox experience and in a way the immersiveness of the game. It's one thing for you to try to play the game in a way, and it's another for that playstyle to actually be there.
And as previously mentioned, Dark Souls also has quite a wide following. Such a 'hardcoe' mode would appeal to such players as well; further evidence as to how such a suggestion is, thinking logically, likely to appeal to many sorts of players. With the trade running, outpost building, etc, Bethesda has shown a desire to appeal to many different players. I intend to capitalize on that to pitch this suggestion to them as it would draw in more players, or make the game feel more real and higher quality to people who would appreciate such a feature.
And again, this suggestion is, objectively from the point of view of programming(IN MY OPINION), not all too effort-demanding. I specifically wanted it to be relatively simple, so as to allow for little resources to have to be diverted towards such a feature, even though it is a feature that could hugely improve the game experience of a variety of players. So if you truly think that this would be hard to implement, and if you are a programmer, and really think you know better, please let me know.