I wan't to role play this game and let Lydia stay dead, but I just can't. Obviously there is a game mechanic in place to keep companions alive as long as possible, so even the devs understand that they are important. When they do die it's because of the stupidest things. A badly timed shout, a stray axe swing by me, etc.
If a dragon doesnt take down Lydia when she's standing right in front of it, but my misplaced firebolt does, then its time to reload. Maybe if I know for sure Lydia died an honorable REAL death, then maybe I wont reload. Also, something to note, the game reload when I die, so.....