This... I can answer! The vast majority of it is due to heat generation due to the console size and form factor.
It's why the Xbox One X size is actually a miraculous display considering the amount of power in a relatively small package (smaller than the less desirable original model and much more powerful)
However, when you don't have the correct set up in a form factor, you risk large failure rates from consoles overheating and affecting other components silently before a big failure hits. The Red Ring of Death is a great example as theories around GPU heating and an untested solder technique we're guessed to be at the foot of it from Microsoft, alongside other theories of course.
So there must be balance between your heating and cooling apparatus. As such, optimal temperatures would factor in size, ventilation, fans, adhesive, and desired graphical output. And this would have long term ramifications of both console design and the resilience of the system to last.
Additionally, you need to be sure that the end user won't be inconvenienced especially hard by the power draw for extended sessions. Most devices are judged by tech sites when being plugged in to see how they would affect energy bills. This includes consoles.
So there's a lot to think about. I think others have stated the Watt draw is asked to be within more specific numbers than I could give so I'll let them answer that part. But it's a very important element of the console design to monitor heat output and heat dispersal through a form factor.