Because 20% crit chance (more crit and even more crit perks) or 25% doesnt matter. 5 ST and 5 LK with one less implant to worry about.
Higher strength means more loot. It also means (Fallout games in general) a hidden boost to knockdown resistance. Its a very tiny effect at 5 but its noticable at 8-10. (Close range, 2-3 hexes. 1 hex away it doesnt matter). Yeah it stacks with knockdown resistance perks and traits.
1 LK gives much more critical chance with aimshots then 1%
to eyes you get +3,4%crit chance for each LK
here is some more information about it
http://www.fonline-reloaded.net/wiki/index.php?title=Aimed_Attackloot wont help you win battle, first of all you need to minmax your build for win, 71 carry weight is enough anyways
also almost every sniper uses jet, 1 ST - 2 jet = -1, if you would want to increase it, you would need to put into it at least 3 SPECIAL points, its pointless to increase ST on sniper
so with 5 ST 5 LK you would have 5 - 2 = 3 ST which gives you nothing but a bit carry weight and you would lose about 17% crit chance to eyes