GRE Vocabulary Building
Imagine this. You've studied your GRE vocabulary words really well. You've practiced writing lots of great essays - you feel good to go!
Then you sit down in the exam and find yourself confronted with the most BORING essay prompt you could imagine. Whatever topic it is that bores you stiff, you suddenly find yourself having to write an essay on it for the next 25 minutes!
This is a real pain in the neck, but it happens often, so you must be prepared for the eventuality. To prevent this causing you a disaster on the day of your test, you should regularly practice finding and expanding a "pretend opinion" on things that you don't care a fig about. You could pretend to be someone else, and say, "People who like xxx would give the following reasons why this is a bad/good
idea: .... " And so on.
The nub of the matter is that you have to be able to come up with an essay on pretty much anything, so practice writing essays as a skill, regardless of the content.