TrippyHippy
Hero
The impact of a mere '+1' or '+2' on Ability scores (associated with Prime scores for Classes) tends to make a big indication of which combo to go with. On that basis, you can see how small changes could balance up some of these things.
Halflings might be chosen for more Class combos if there was more flexibility on Ability bonuses. You could get this by having a greater variety of sub-Races. If there was a sub-Race of Halfling that gave a +1 bonus on Wisdom scores, you might see more Halfling Druids, for example. Likewise, Gnomes used to be considered excellent choices as Bards in previous editions, but because there is no Charisma bonus in this edition, the combo is sub-optimal and so Gnome Bards are practically extinct.
As I said above, the reason why Half-Elves are so highly rated (as a 'rare' Race) is because they are overpowered. They take the best bits of the Elf, an Extra +2 on Charisma and have the versatility of Humans with a +1 on any two Ability scores following on. That versatility just about makes them best at every combo - which is a problem, I think.
Halflings might be chosen for more Class combos if there was more flexibility on Ability bonuses. You could get this by having a greater variety of sub-Races. If there was a sub-Race of Halfling that gave a +1 bonus on Wisdom scores, you might see more Halfling Druids, for example. Likewise, Gnomes used to be considered excellent choices as Bards in previous editions, but because there is no Charisma bonus in this edition, the combo is sub-optimal and so Gnome Bards are practically extinct.
As I said above, the reason why Half-Elves are so highly rated (as a 'rare' Race) is because they are overpowered. They take the best bits of the Elf, an Extra +2 on Charisma and have the versatility of Humans with a +1 on any two Ability scores following on. That versatility just about makes them best at every combo - which is a problem, I think.