"If we didn't enforce the code, what would happen when the fixtures are changed?
The load could be higher than the load at the time of installation"
You still are limited by a single 20a O/C device. How much bigger can the load get?
BTW the code does not protect against the next stupid thing an installer might do. You can put in a 400a fused disconnect with 225a fuses and you only have to serve it with a 225a rated conductor.
Sure someone could come along and shove in 400a fuses. That is not addressed.
