Many of the rules are there for safety, it’s not that hard to make a car so fast that the limiting factor is the driver and then the race becomes a contest of how willing to die your driver is.
Even with humans driving remotely, it's not very profitable. Drone racing is about as successful as RC racing has become. People don't take sports seriously without humans being directly involved.
And if their heart rate drops below 149bpm they get sacked. Boring is subjective but you're watching it wrong if you didn't find the last championship exciting.