As for why such a measly circuit?
Keep in mind this is not a car, where accessories such as 50-watt stereo amps could be supported by the factory wiring.
Some early owners whined about not having a convenient place to plug in their phone's car chargers, so Yammy added it on. The ignition switch supplies power to the ABS computer, the ECU, hazard light (and turn signals,) signalling systems (brake lights and horn,) headlights, all directly through the switch, which carries the full load of those systems, as they are not energized through relays. Now we greedy riders want an accessory power plug. They put it in by tapping that same line off the ignition switch, adding another fuse, and running it to an accessory plug. They didn't have a lot of headroom to play with, but who needs headroom for a phone charger?
Some may note, "Hey, Walter, you dumb ^$%#!!!! The headlights are on a relay!!!"
Yes, they are, but not to relieve the load. The headlight relay coil and load are both on the same fuse! (So I am not a dumb ^$%#.) The only reason the relay exists is so the ECU can turn the lights on when the motor starts. Why, it's almost British in its logic, having a relay and its load on the same circuit!!
Anything significant you want to add to this bike needs its own wiring either direct to the battery, or through an accessory fuseblock. Personally, I don't need a plug for an air compressor. I've hard-wired one and it stows under the pillion seat.