People who pay over $100,000 for an ultra high performance car that was marketed as having the capabilities to do a 1/4 mile run in that time care. A lot. It's why many of us paid the extra amount over the lesser offerings and other cars that we could have bought. It might not matter to you, but it looks like you didn't pay the premium for the performance version of the car. I did and I care.
This!
The 85D with the same options I have would be $109k, the P90DL was $141k. Not only are you paying over $100k, but you are paying about 1/3 more for the extra performance and about $3k more in taxes. With Tesla you can't make any meaningful aftermarket performance modifications, you're stuck with what you get. So there's even more reason for it to do what they say it can do. I understand that in the "real world" having a car that has incredible performance really isn't needed and the vast majority of people don't care or want the power, but some of us do even off a track.
With the P90DL the 2.8s 0-60 and 10.9s 1/4 both indicate an improvement in performance above 30, which is what we are paying $13k extra for. The money was spent for the improvement in performance, not the specific number (at least for me) like how I paid for a specific color of paint. Tesla originally claimed 3.2s 0-60 and 11.8s 1/4 mile for the P85D, Motor Trend got 3.1s and 11.6s. An improvement of 0.4s in 0-60 should result in a 0.4s improvement in 1/4 mile. However, they also said there was improvement in reaching top speed, so a 11.4s 1/4 mile doesn't cut it because that should be achievable simply with the 0-60 improvement.
I'm very happy with the performance of my car over a P85D so I'm not upset, but look at it this way. MT got 11.6 and we're expecting around 10.9... think about paying $14k (with taxes) and instead of getting a 0.7s improvement you're getting a 0.2s improvement. Considering how crazy people think we are for spending $2k per tenth, think about paying $7k per tenth.
That is why an additional 0.5s matters and if you want to reduce it down to money instead of the experience of the power... 0.5s can be viewed as $10k at that rate.