star trek - Why can't a Federation Starship's transporter history be used to bring someone back to life?

I've always been a little confused by the fact that when a crew member dies they don't just use the transporter history to bring that person back. I'm aware that this wouldn't make for good TV, but I was wondering if there was a more technical reason.

Answer

In early canon, the transporter log was exactly that; such and such a person transported to these coordinates at such and such a time. They were likely entered by the person manning the console instead of in any automatic fashion.

With more advanced transporter technology, such as the ability to "save" a person's pattern in the transporter's buffer, there is the possibility of bringing someone back to life. In fact, a Voyager episode (VOY:Jetrel) deals with exactly that; Neelix's backstory is that his home colony, Rinax, had all life wiped out and was rendered permanently uninhabitable by an enemy's use of a WMD, the Metreon Cascade. Neelix was on the Talaxian homeworld at the time, but lost his entire family to the weapon. We learn over the course of the episode that the Haakonian scientist who developed that weapon is attempting to atone for his actions, and eventually comes up with a plan to use Voyager's transporter to resurrect Rinax's victims, as their "patterns" remain in the residual radiation of the moon's atmosphere. He fails, but the attempt redeems him in Neelix's eyes.

In the TNG episode "Relics", the Enterprise comes across a Dyson's Sphere while investigating a distress signal. The ship sending the signal has crashed on its surface, and the away team learns that the transporter on the ship has basically been used as a stasis pod, using the transporter to dematerialize a human (Scotty), then hold them in the pattern buffer indefinitely before their rescuers re-enable the rematerialization half of the sequence to get them back out. However, the imperfect nature of this approach is obvious as a second "stored" person's pattern has degraded too much to save.

So, the thought has obviously occurred to several characters in the canon that transporters have the ability to create life as well as recreate it. But, other than a couple episodes of cloning (such as Thomas Riker, a duplicate of William Riker who joins the Maquis) it hasn't been widely successful, to say the least.