Just to lay out some numbers: let's say I'm committed to playing a full plate + tower shield Fighter. STR 16, DEX 12, CON 15.
As a Dwarf, to reach CON 15 costs 5 Attribute points at creation. You can end up with STR 21 at max level.
As a Human, to reach CON 15 costs 8 Attribute points or creation. Or; you can spend 6 Attribute points for CON 15 at the opportunity cost of having STR 20 at max level. A small, but significant, uptick in cost.
As an Elf, to reach CON 15 costs 13 Attribute points; but I get 2 back from DEX, so the net is 11 Attribute points. Or; you can spend 6 Attribute points for CON 12 at the opportunity cost of having STR 18 at max level. Or some combination. But here the difference in cost is clearly evident.
You can look at the above discrepancy and justify it in two different ways.
- You can ignore all other Feats, as was MAB's initial argument, and take the Feat as given. If you don't like it, don't play Elf Fighters.
- You adopt a holistic perspective and look at all other Feats in some Ability-gated strategic choice tree, as was EO's argument; in which case the existence of a feat like Armor Skin for CON is balanced by some choice like Shield Parry for DEX, or so on. Which means that playing an Elf Fighter who doesn't go for Shield Parry becomes a suboptimal strategy.
You have to admit that it's a pretty strange artefact of design where the full plate/tower shield Elf Fighter is relegated to a suboptimal "fun" build like Half-Orc Bards or Gnome STR Fighters.