Just remember that if you want to be able to remove nice mods from weapons or armor you find, to reuse on some of your other gear, then you'll have to have at least one point in Gun Nut and/or Armorer, to do so. Most mods can't be removed unless you have the ability to craft a basic-level replacement mod to put back on. I think this is kind of stupid, really- you should be able to remove any mod from any item, and have the remaining item simply be broken down for parts in the process (if you don't replace that mod with a lesser one).
You can get most of the good damage and accuracy improvement mods on guns by recycling mods off of stuff you find, if you have the minimum 1 point in Gun Nut.
Also, Lockpicking and Hacking aren't crafting perks, and you can make it through the game without putting points in either, I'm pretty sure. I believe Novice level will get you through most of the quest-required locks or hacks. You'll be a lot harder up for ammo and chems and other stuff though, as locked containers and storage rooms contribute huge amounts of those. I'd put at least one point in Lockpicking, as probably 75% of the locks in FO4 can be picked with it only up to Advanced level. But if you stick with Novice level, yer gonna be hurtin'.
As for not putting any points in weapon skills, er, why not? Unlike crafting skills, which would seem secondary to gameplay, the ability to do more damage with your chosen weapon type is a pretty basic, and pretty *important*, thing to do. If your purpose is to greatly weaken your character to make the game much more difficult, then yes, that would be a very, very good way to do just that. When Bethesda took away the skillpoints RPG function which had been used in previous Fallouts as the primary means by which to improve your character's damage output, they replaced it with these weapon-specific perks in FO4. The monsters get tougher and hit harder as you level up, and the main way by which you get tougher and hit harder to keep up with them, is via those weapon buffing perks.