This is a place where we can stray from the other 5-15 topic
Reno says he has a microwave with >15a draw and the the mitigation was given that this would usually be on a 20a small appliance circuit so it is OK.

The problem with the assumption that the microwave will be on a "small appliance circuit" is that these things end up in dorm rooms and other general lighting areas.

We do get some safety from 240.4(D). They build the 80% safety factor right into the maximum breaker size allowed on a given "small conductor" (14ga & 12ga in particular)
I have seen 5-15 plugs on lots of things that have no business on a 15a circuit tho.
I have a Brinkman smoker with a 1650w heater and a 5-15.
It won't even run on a 15a. It trips out in a few minutes.
This thing tripped the breaker when we tried it at our office on the outside outlet. The work around, that made my teeth hurt when I saw it was to drop a 16 ga cord out of the 2d floor window and plug it into an unused circuit up there.
It worked but I think it was just because of the voltage drop in 50' of 16ga cord. You could cook a hotdog by wrapping it in the cord
I had a dedicated 20a installed out there, just for the smoker.

The other issue brought up was that we only size general lighting circuits to the square footage of the home, not by the number of outlets.
Whether the number (3va per sq/ft)is right can be argued but I think the logic is sound. People are going to put the same equipment in a room, regardless of how many outlets there are. The issue addressed is making sure there is a safely available place to plug it in without extension cords or cords crossing walk ways.
Certainly there are a few power hogs that can be plugged in like space heaters and vacuum cleaners but most things actually use negligible amounts of power. I have an entertainment center with a TV, a PC, 2 satellite boxes, a DVR, TV amp, lights, ethernet switch and a number of other "wall wart" type equipment on 2 UPS units. There are at least a dozen things plugged in. Total draw is less than 6 amps with everything going.

Greg, there's a world of difference between good design and code compliance.

One of the big requirements for good design is to know what is needed. That's why some folks drive jeeps and others station wagons- different needs.

That's why I'm in the process of measuring my appliances. I'll soon have a thread on that topic.

Greg:
Do you know what the smoker was actually drawing, vs the nameplate?

It is out in the shed. I will try to dig it out and give it a try.
The fact that my voltage cruises around 124v doesn't help.