I disagree completely.
I just finished a Hard (scaling to Very Hard later) playthrough with a sniper character. IMO, Luck isn't necessary at all (but it doesn't hurt, obviously).
Perception, OTOH, is vital, as is Agility. Between the two of them, you have most of the ways to increase your chance to both hit and the chance to do overwhelming amounts of damage in a single hit. As a Sniper, being able to kill multiple enemies without wasting Action Points in VATS is essential, especially when they're bearing down on your position. Consistently doing massive sneak attack damage (Perception + Agility) is, IMO, better than periodic bursts through critting.
I'd start with Perception 7, getting 8 from the Bobblehead in Concord asap. Set your Agility to 6 and use the SPECIAL book in Shaun's nursery to upgrade it to 7. After that you put Int to 5 (raising to 6 with bobblehead so you can make recon scopes, generators, etc) and Charisma to 5 (so that Local Leader is within reach, plus Black Widow/Ladykiller).
Luck will take a Bobblehead + a leveled perk point later to get up to 3 (because you do want Bloody Mess).
What this gives you is (assuming maxed perk):
Rifleman 5 - 100% additional damage with rifles - Sniper Rifle, Laser Sniper Rifle, Plasma Sniper Rifle, and Gauss Rifle are the most important weapons for this build. Your off weapon should be something like a combat shotgun and not the Deliverer unless you want to spend perk points on Pistol
Sniper 3 - +25% additional accuracy to headshots in VATS (add MacCready's perk for another 20%, assuming you get it bugfixed with a mod on PC), the chance of knocking any enemy who survives a sniper shot down, and rock steady aiming when looking through a scope. With the Stabilized trait on both arms and this perk, the aiming point on the sight barely moved for me. I would headshot without VATS constantly.
Penetrator 2 - Within reach, but not necessary. Headshotting people behind cover is, simply put, amusing. Also, when enemies are on alert and constantly ducking behind things, you don't lose shots to sudden movement.
Lady Killer/Black Widow 3 - TBH, this is just for the damage bonus against half the humans and ghouls you encounter. 15% is 15%. Plus you'll need Local Leader to do anything with Settlements of note and this is on the way.
Gun Nut 4, Scrapper 2, Science 4 - This is how you make the best guns, the best scopes, and get the materials for them.
Sneak 5 - Vital. Max this first and foremost every time. Get armor with Shadowed trait (as a sniper you won't move much, so muffled does less for you, but shadowed prevents them from spotting you after they go on alert). Stealth Boys are amazing for tight confines in buildings where you may not get an opportunity to park a quarter mile away and kill them all.
Mister Sandman 3 - Amazing. Ignore the 'kill in their sleep' bit, it doesn't matter much. Your guns with silencers do up to 50% additional sneak attack damage. This stacks with other sneak attack bonuses. When building your guns. Put. Suppressors. On. All. Of. Them. No exceptions. If it can't have a suppressor, you don't bother with it. (Fun Fact: Gauss Rifles can have a suppressor. Good times, good times.)
Action Boy/Girl 2 - More AP is better AP. Between a high agility and accurate shots, you will and will want to take a lot of VATS shots. The best times to use VATS, IMO, is when very quick twitch skills are required (enemy barges around a corner, something suddenly goes hostile from neutral, radscorpion bursts out of the ground). If you're always walking around in stealth (which is normal after you get Stealth ranked to 4), you may get a sneak attack bonus still if you queue up the attack quick enough. Afterwards, when sniping with less pressure, trying to get your kills in based off your skill with the scope is the way to go. Just be accurate and don't be afraid to go center mass if you can't get a clean headshot -- once your sneak attack bonus is high enough, even hitting the leg can kill them.
Ninja 3 - And here we go. Increasing base sneak attack damage to 3.5x normal damage for ranged weapons. A vital skill you must have for this build. Combined with Mr. Sandman and Deacon's Killshot will get your average crit with scoped, silenced guns to 6.3x normal damage.
Bloody Mess 3 - 15% additional damage is 15% additional damage, and this applies to everything. Go get the bobblehead off Spectacle Island (just walk from Warwick Homestead in the T-45 armor from Concord). You should have one leftover point in CharGen to get it to 2 base. (That'll leave STR and END as 1, but who cares? Those stats just don't matter much to this build in the end).
If you want Armorer to mod out your own armor or to tinker on Power Armor, go to the Mass Fusion building and clear out the Gunners during your early levels and get the Bobblehead, then spend a level's perk point on it. That'll unlock Armorer.
At this point, a standard (non-legendary) .50 calibre sniper rifle should baseline around 375 damage. A sneak attack by you will hit for 2362.5 damage. This means it surpasses the damage resistance threshold for even X-01 mark VI power armor.
As an FYI, the way your Damage Resistance works is that it compares the values of the incoming damage to the DR of the target and on a 1:1 scale it halves the incoming damage. If DR exceeds the damage, then the remaining DR (with huge diminishing returns) continues to reduce the incoming damage. Hitting power armor with low damage weapons is like spitting at a wall due to this; yes you may wear them down but that 50 damage your gun does is getting reduced first by half, then the other 1000+ points of DR is doing everything it can to squash it to near zero (you will always do 1 point of damage). This works in the other direction, too. The more damage you do past the DR, the further away from 50% damage reduction you get, down to the single percentile range.
So... if I should someone in X-01 mark VI armor with that rifle, and it's a sneak attack, their 1850 DR will be exceeded by over 500 points (512.5). The way the math works (and the equation's a pain to do, so I'll guesstimate), the damage being so high should reduce the % of incoming damage reduced from 50% down to about 35% (very roughly). That means the target still takes 1,535.63 points of damage.
How many NPCs do you think can survive that hit? Upgrade to a Gauss Rifle or get a Sniper Rifle with the Instigating or Two Shot traits and watch the damage roll in. Instigating, for instance, turns the above 2362 damage hit into a 4725 hit and nothing survives that without being a Behemoth sized creature (even then...) or some ridiculous Legendary Supermutant bullet sponge. I had an Instigating Sniper Rifle and one shot Swann in Boston Commons with it, as an example.
Critical hits aren't even necessary, so I never relied on them (though obviously used them as available). You will use VATS enough to make them come up with some frequency, but would have to spend a fair few leveling perks to get Luck much higher.