I agree mostly with Michael's answer. However, in certain scenarios, randomness not only becomes useful but necessary as well. As recently to re-calculate a price(floating number), I needed to randomize few input values so that application is forced to re-calculate price on every test run which will not be possible with static price value.
Also on randomizing numbers in decimal points up to the large range, I found an issue where the application is incorrectly rounding off the price(after complex algorithm calculation) after certain decimal points which is not acceptable.
This issue was undiscovered over a long period with static values.