I like to be thorough, it prevents making a mistake when you enter the seed. Let's say you created Seed A, and wrote down Seed A. You wiped and restored the wallet, but when you entered it, you typed a wrong word. Murphy's Law made it a valid seed. Now you have a working wallet, but your seed backup doesn't match.
If you would have written down the first address created by the wallet after it first produced that seed, you would have caught this mistake.