The only practical benefit I can imagine is that it puts a deadline on the damage from a root compromise. Not sure how much that's actually worth though. If yo

The only practical benefit I can imagine is that it puts a deadline on the damage from a root compromise. Not sure how much that's actually worth though. If you're designing a device that cannot be updated (or won't be), you probably shouldn't use Web PKI. Even if the roots didn't expire, I'm sure the BRs would eventually evolve to preclude issuing leaf certs compatible with the devices.