Puncture and abrasion resistance:

I don't think straight up punctures are that big of an issue but the test did show a footprint helps. Having something to take up the abrasion instead of the tent floor is something I like having. Grooming a site isn't realistic a lot of the time. You'd be amazed how much unseen nasty stuff a baby can vacuum to their mouths from a square meter of carefully cleaned ground. Having to do that for a tent sized area would be chore / impossible at times.

Waterproofing:

Is this a thing?

Condensation:

What grinds my gears with this test is that it was performed with the wrong type of tent. A dome tent such as used in the test doesn't have large enough vestibules to cause an issue with ground condensation. A tunnel tent on the other hand often has a vestibule that's near the same size as the sleeping area. If the ground isn't bone dry, you can be sure some of the ground condensation will end up on the tent. You cover that exposed ground area with a footprint and the ground condensation has much less chance to rise to the tent from.

Additional benefits:

Having a floor in the tunnel tent vestibule is really nice especially if the ground is wet, muddy or otherwise nasty. Prevents a lot of the crud getting inside the tent. Helps with insects too.