To begin with, my first answer in this thread was just tongue-in-cheek. This is just one of those never-to-be-heard-from-again applications with fantastic potential of the week.
Hell, if we count those, the Federation wouldn't probably even
need the nanoprobes technology to revive the dead.... all they'd need is a
single healthy cell and the transporter recipe used in
Unnatural Selection to "uncorrupt" dr. Pulaski's DNA. If it can work on such a deep molececular level and undo all microscopic and macroscopic damage in the body (such as aging) as a consequence too, it should also be able to reverse a relatively simple lethal head wound.
Have you seen the # of issues that should "Never Happen" or are virtually impossible in Aviation and what really occurs? Worse case scenarios do happen IMO. And testing for working in the heat of battle is INCREDIBLY hard.
Oh, I know, being an engineer myself. But this is Star trek, not the real word, in which the
engineers often exclaim that something cannot possibly go wrong (only to find out it still does). The real reason for that is of course dramatic tension- the same reason they have been in space for 350+ years yet every other week encounter a nebula or anomaly of a type never encountered before. But in-universe it seems they have an almost naive belief in the perfection of their technology, and you would expect them to get a little more realistic after a few of those experiences. Mostly, they don't. So either I'd have to assume that in everyday life their technology is
really that failproof and what we're seeing on screen are highly exceptional circumstances, or I'd have to assume they swallow their own Starfleet propaganda and not even reality can convince them otherwise.