I'm far from a pro race car driver/engineer, but I have hundreds of track hours and have been pretty deep in the weeds on reading about handling dynamics, so I'll take a brief shot:
The biggest advantages to having a lower, more centralized center of gravity are a lower polar moment of inertia= how quickly a vehicle will change directions, and less weight transfer= all four contact patches of the vehicle doing more work, whether it is in accelerating, braking, or cornering. Where the weight is matters, too, as low and centered means it has less overall impact on these things. Lighter is always better, as any Colin Chapman fan of Lotus fame would attest!
Away from the track, and trying to be a bit more on topic, its impact on future vehicles can mean that Teslas will handle better without an overly high spring rate, which means a more comfortable ride. I.E.= they'll have better "real world" handling that more drivers will tolerate than those of us who sling around cones in parking lots or the smoothness of most road race courses! Probably the biggest benefit though is if you can reduce weight without decreasing energy storage it means you get essentially "free" longer range. Consumables such as tires and brake pads (hardly a concern in a Tesla already) will also go down making a small benefit to overall maintenance costs.
From an investor perspective, it means Teslas packs will make the car more desirable while also decreasing their manufacturing costs, and it hardly gets better than that!