I don't see how using the same tools in PSP, or whatever high-end art app you care to mention, would make the process much easier. That's why I don't see the fact it was done in MS Paint is particularly relevant.
You don't see how drawing in Photoshop is easier than
drawing in MSPaint? C'mon, you're joking. In this
particular example, consider: Layers, brush-attribute
control, colour management, masks ... man I could go on forever.
It is much, MUCH easier to create something in PS as
opposed to MSPaint. I will say again, tools matter. Unless:
If both tool A and B have the same feature for a certain process then there's no arguing.
I can mostly agree with that.