I agree that the 30A RV plug looks a lot like some 240V high-capacity connections (like the welder receptacle in my garage); however, the combination of pin sizes, positions, and angles follows a well-understood set of standards in the industry, which ensure that if they plug together, they have compatible ratings. The biggest risk is that someone puts an inappropriate connector on some circuit or device - it's a good thing that the easiest thing to do on an RV (buy the one everyone stocks in RV stores) is also the right thing!
Actually it is quite handy to have a 30-15 Amp and a 15-30 Amp conversion plugs...
...Our 16' Scamp is quite happy with the 15 Amp power since we don't have an electric water heater and the current draw for the air conditioner is about the same as a small household window unit. Lights etc. are 12V through the battery/inverter.
I think this means putting a 15-amp section (two adapters and a 15-amp cord) into an otherwise 30-amp circuit (30 A supply and trailer with 30 A cord and circuit breaker or fuse). If so, neither the supply side (the campground circuit) nor the load side (the breaker or fuse in the trailer) will limit the current to 15 A, which is potentially dangerous.
Each piece individually is okay and has a legitimate use, but the combination is not good.
If I have misunderstood and the trailer is fused or breaker protected at 15 A, then there's no problem; however, if not, then I would certainly not be comfortable relying
on the fact that normal loads would never exceed 15 A - I would change the trailer breaker or fuse to match the wiring capacity, presumably to 15 amps.
has a 30 A breaker in its AC panel, and a 30 A built-in cord. I do
use an adapter to plug it into a 15 A extension cord; however, the cord is supplied by a household outlet which is protected by a 15 A breaker in the house panel.
In the end, something has to [b]limit current to the least capable element in the circuit.