We would have really liked to know what happened while we were underway to the scene in this scenario: https://youtu.be/QOM5SzxEFGU?t=1m50s
And a driver under a few 100kg of Tecpro barriers takes a while to get to: https://www.youtube.com/watch?v=jJN-b-ovkQQ
It wasn't until 2014 when Jules Bianchi crashed in Suzuka that F1 saw another death during a race. Now, a biometric sensor probably would not have helped Jules, but it may have alerted the medical team to the seriousness of his injuries. Oximetry and heart rate may not have indicated much, but I think it's a great first step towards other sensors that could eventually be incorporated.
F1 tries to be at the forefront of automotive technologies. Driver safety always has been and should be a huge part of that.
The Hans device, protective monocoque, wheel tethers and other incremental improvements are nothing short of stunning, and though he has many legitimate gripes against him, Max Moseley was key in pushing this forward in his time as head of the FIA.
But we can all agree no one like the halo... (I kid...)
Someone will be at the scene asap regardless of data. They will check for fire and breathing issues. If either driver isnt talking or car on fire, driver is comming out now. After out, or sometimes before, gloves are off and other sensors applied. Decisions such as the use of a spinal turn on danger, not medical data: always a spinal unless car about to explode. I dont see the case for this data as it only means something long after more apparant dangers have already dictated decisions.
(In my work i regularly draft ERPs for aviation crashes, a similar senario. I just last month completed a hypoxia course in a hypobaric chamber where o2 sat was a very big deal)