In my opinion, the modders' survival modes in Fallout 3 & New Vegas were much better thought out.
Probably true. I never really got into any of those.
I think we'll eventually see mods that tweak Fallout 4's Survival Mode into something better, and that it'll be better overall because there are more tools available.
There are already several mods which defeat the limited saving in Survival Mode to one degree or another. I think the one that restores autosave on entering / exiting a building goes a long way to fixing that problem.
Another mod which I think helps is
New Recipes, which gives more ways to make food in Survival. In particular, it makes all that nigh-useless wild food (tato flowers and the like) into something you can use.
I played briefly with
Brutality, which is another Survival-focused mod, and I think it needs work. It cuts the health back of everything, both enemies and the player, which isn't a bad idea. But to balance that it also nerfs the weapon skills (Gunslinger, Rifleman, etc.) to the point where they're useless. It really ought to replace them with something that's as beneficial as the other perks, but not damage-focused (given the drive to flatten the damage scaling).
It also makes the Minigun ridiculously powerful. Per-shot damage is high, fire rate is high (of course), and it's armor piercing. The encounter with the Concord Deathclaw is trivial because you have a minigun.
Which arguably maybe it should be. Miniguns are
supposed to be something extraordinary, it's just that the game skews that by handing you one practically at level 1, along with a set of Power Armor. In Fallout 1 terms that's end-game equipment.