If you insist on an ASI bump, why tie it to anything? Untie it from race and from class, and make it part of the
Determine Ability Scores on page 12 of the PHB.
Just allow PCs to select their
Ability Focus, and increase one ability score by 2 and a different ability score by 1, regardless of which method of ability score generation (rolling 4d6-L, standard array, or point-buy).
Again,
@clearstream, I'm not knocking what you're doing, just offering an alternative. The idea of Ability Focus is your character has chosen during their development/upbringing/whatever to do something to make that ability better. For instance, suppose you use the standard array for your game, and want to be strong so put the 15 in STR, but don't want to be unwise even though I end up with a WIS 8. So, I can use the +1 in STR and +2 in WIS, getting a STR 16 and WIS 10.
Nothing tied to race or class, I could be any race and also any class which might want a high STR and average WIS (Barbarian, Fighter, Paladin, or Rogue maybe...).