I am landing on a runway where my data says I can land, and I add additional margins with my technique.
I can definitely see your logic but I don’t share your assessment of the risk. Why I don’t share it is probably a complex mix of life experiences, personal motivations, and expectation. Everyone will have a different combination of these so it is inevitable that where humans are involved there will be very different assessments of the risk of one particular activity whether that be a child climbing a jungle gym or a 737 Captain landing on a contaminated runway.
Some of my reasons for diverting in the circumstances that you have given are as follows,
1/ The braking action may or may not be as reported. There are many many cases of this reported globally on an annual basis and I have experienced it myself so I have an expectation that if I do this job long enough I will experience it again, when I do, I want more than 255m wiggle room (1700 x 0.15)
2/ The wind may not be as reported. I can mitigate this to a certain degree through knowledge of my expected ground speed approaching the threshold but I also know that if my brain is working hard on the required scanning both inside and outside of the aircraft my assessment of ground speed in the last 100ft might be left wanting.
3/ The machine itself is not infallible. Once I have selected reverse thrust all of my passengers lives will be relying on mechanical cylinders,hydraulic lines, speed brakes etc to operate as advertised. There is a very small chance that this might not happen. ( I acknowledge that this chance is very slim).
4/ I am not infallible. I have made mistakes in the past and I assume I will fly a less than perfect flare and thrust reduction in the future.
5/ The FAA SAFO issued in 2015 suggests that I should exercise conservative judgement of braking action even when the data suggests that I can legally land. This SAFO was motivated by incidents and accidents where braking action was less than anticipated.
These things combine to create a risk assessment in my mind that is more conservative and would result in a divert. That variation in decision making is to be expected. Let’s just hope it ends well for us all.