Our regeneration is not quite the same as reincarnation or resurrection. If we are fully killed before we regenerate then we stay dead. We do have the capacity to resurrect as well, but it is supposed to be restricted to those who have received approval from the High Council of Time Lords. Gaining such approval is almost always political, and has little to do with who deserves more life or not.

What did Glorfindel do to receive such a gift?