Because accountants mostly.
For large businesses, you essentially have two ways to spend money:
This leaves companies in a slightly odd spot where from an accounting standpoint, it might look better on the books to spend $3 million/year on cloud stuff than $10 million every 5 years on servers
Because Google is great at naming things, you might be getting confused between a few distinct products:
500w TDP Vs 360w on previous generation - cooling this thing is going to be fun