These are called tropes. They are a useful tool to tell a story. These trope can also be used to do the unexpected and making that minotaur rogue will surprise your players or their foes. Just as the armored dwarf casting a fireball would be a massive surprise.
Tropes create expectations and playing on these expectations is what makes the game interesting. We all know that orcs don't cast spells. And boom! An orc wizard comes and shakes that belief.
But without these tropes, there is no expectations and thus, no surprise. This is simply because every races can be anything without a cost to pay in effectiveness. You lose the element of surprise. You go from: "What? That orc throws us a cone of cold!!???" To "Ho, that orc was a wizard. (Yawn)."
I mean, Orc Shaman is a trope, too, but I'll argue your point.
Here's the thing. Other forms of media use tropes in their storytelling, and they don't have to detail fixed racial ability modifiers to do it. They can just say, "Wookiees favor bowcasters and are adept with mechanical repair." and "Vulcans favor logic and use strict mental discipline to build mental fortitude as a path to self-actualization." and "The Elves of Mirkwood favor long knives and the bow." You can just
say it and it's so. In-game, you could give Wookiees automatic bowcaster and Repair skill proficiency. You can give Vulcans automatic Insight proficiency, and advantage on Int, Wis, and Cha saves. You can give Elves of Mirkwood proficiency with daggers, short swords, and bows. You don't need a +2 Str, +2 Int, or +2 Dex?
Furthermore, there are lots of tropes
in the game itself that go
against the current racial ability modifiers. High Elves are supposed to favor longswords. Since when have you seen one do that in game? Their Dex bonus makes rapier the superior choice, so why did the whole race bother with longswords? Tieflings are supposed to create suspicion and fear from their appearance, but their bonus to Charisma means they're more likely to be trusted (faithfully or otherwise) and liked by those they meet. Half-Elves are similarly supposed to be unwelcome in both Human and Elven lands, but their Charisma bonus doesn't really seem to follow from that. And why exactly do Dragonborn get Str and Cha instead of, well, anything else? Because Sorcerers have a Dragon path? So Dragonborn are linked to Sorcery? All of them? Yes, dragons are strong and carry a mighty presence, but they're also tough, cunning and wise. Indeed, the only thing a dragon
isn't is nimble, which is part of why they're so fearsome. So... why Str and Cha? And if Kobolds are also draconic in origin... why do they get a bonus to Dex and a Str penalty?