It's the nature of souls to decay over time, even in life. It's difficult to retrieve what was lost when that happens, and even if it weren't, the problem is keeping the information contained there in one piece. People have struggled for a long time to keep themselves alive beyond their body's limit, or to try and resuscitate the already dead, but they've all been faulty and imperfect practices at best.

...I'm not sure the dead have any need for noses anyway.