Nice article! The resulting Pareto front really highlights how hard game design is. You can get millions of possible combinations but the reality is that only a handful of them will ever happen in a competitive environment.
As a game designer, you want to add silly and suboptimal things to your game. Don't fall into the trap of thinking that every decision must be perfectly balanced and equally weighty, because your game will turn out bland and textureless. And beyond the considerations of "optimal" play, putting suboptimal options into your game can serve as both a way of naturally selecting difficulty without having to implement ungainly difficulty sliders, and also accommodate fun/silly challenges for people who just want to mess around.
In a sufficiently complex game every build is on the pareto front as it optimizes some specific cost function.
However, if your one and only goal is winning I suspect that the high dimensional vector space will end up not looking so high dimensional once you account for the correlations between the different features you use. This is already clear from the very strong correlation between speed and accelaration.
[]I myself have played MK64 a lot and sometimes the goal was simply to see the world burn, standing on a corner with a shell waiting for the what would've been the winner of the race. Fond memories.
Even if you're only optimizing for race times, in the case of Mario Kart, the choice of track will have a huge impact on the optimal kart selection. Tool-assisted speedruns pick different karts for different tracks.