I thought NV do have a functional crafting system that allow you to craft special makeshift weapons and explosives? or do you mean you like the idea of more blueprints collected should give you weapon with better condition?
You can only craft one weapon and that is the Dog Tag Fist. You get the schematics from a NPC after doing a quest, so that is kinda like the blueprints (and I like it).
There are quite a few explosives, specially with the Mad Bomber perk.
But I think it would have been better, if Obsidian had made blueprints of the more powerful explosives from the Mad Bomber, while allowing the others to be crafted with appropriated skill level (so we wouldn't need a perk to craft them,) and then made that perk work like the Warmonger from Fallout 3's Broken Steel DLC (unlocks the 3 levels of all the Schematics without having to find them all).
I don't like the idea of a character having gained a level, pick a perk and then mysteriously know how to make these powerful explosives. It would have made more sense (to me) that the character would find the schematics for them instead. It also gives a reason to explore some places that can be considered by some as "empty". I don't mind the crafting of less powerful explosives without needing blueprints.
For example, in FO3 the most powerful grenade and mine are only accessible by crafting them using the blueprints (Nuka Grenade and Bottlecap Mine). While in FNV you have to have a perk from a DLC to be able to craft the most powerful grenades and mines.
I don't know why, but having access to some weapons locked behind a perk doesn't sit well to me, I rather have it accessible to every character, if they are willing to explore, do certain quests, etc. I don't like to force players to pick a specific perk to access the more powerful weapons of a certain type.
I guess it might be just me, who knows. But if it's just me, then this opinion is even more unpopular, fitting this thread even better.