Why wouldn't you play a half-orc cleric just because you don't get a bonus to wis? Why can you only play classes with optimal stat distribution? That, to me, seems like a much bigger shortcoming in the system.
You're right, sadly the system feels limited that way. For comparison, racial bonuses aren't nearly as limiting in Pillars of Eternity because in that game the effectiveness of your class doesn't depend on any single ability, so you don't need to have Intellect above a certain threshold on your Wizard in order to feel viable.
Here's the thing: per base rules you can only achieve a 16 (+3 bonus) if you receive at least a +1 from race and starting with a 15 is terrible. The entirety of DnD5e is balanced around the assumption that you will start with a +3 bonus to your main thing. All companion characters reflect this too, having a 16 or 17 in their primary ability. Therefore, starting with a 16 Wisdom as a half-orc cleric puts you right on curve, whereas if you start with a 15 you will forever be behind Shadowheart.
