Also, it wouldn't really look nice - a typical stainless steel dishwasher looks clean - a microwave and oven (hopefully) look clean and tidy through the window. But a windowed dishwasher? Half full of dirty dishes for most of the day, and even when the dishes are clean they won't look neater than a plain stainless steel finish (or whatever finish you prefer)
Also, it wouldn't really look nice - a typical stainless steel dishwasher looks clean - a microwave and oven (hopefully) look clean and tidy through the window. But a windowed dishwasher? Half full of dirty dishes for most of the day, and even when the dishes are clean they won't look neater than a plain stainless steel finish (or whatever finish you prefer)