Like I say, it's multiplicative.
You don't deal 100 + Str*5 + Warfare*5 + Weapon*5 for physical damage
You deal 100 * (1+Str/20) * (1+Warfare/20) + (1+Weapon/20)
So let's say you have 2 points to use and Str is at +2
You get both poly, it becomes 4 str
100 * 1.2 = 120 damage
Let's say you use that 2 points, 1 in Warfare and 1 in Weapon
You get 100 * 1.1 * 1.05 * 1.05 = 121.275 damage instead along with the secondary weapon bonus like crit chance.
So if you invest in just Poly, you deal way less damage, has less benefit and also, with skills having skill point requirement now (Like Teleport now requires Aero 2), Poly will just result in less skill being usable as well.
And no
Con sucks. Perma CC > bloated health.
Wit is bleh now. No longer does Ini give your whole team action. You and enemy team always take turn from highest ini to lower ini. Your whole team can have 1000 ini but only one of you will get to act before an enemy does too.
And MEM isn't that useful because you gain it as you level anyway along with gears. It used to be a thing with mage who can do everything but with the extra skill point requirement, you can no longer just dump 1 point into each magic school and have all the useful spells.