Hollow items add Luck as your Hollowing increases, up to +10 at 99 Hollowing. So, the more you die, the more of a bonus you get to your Luck (and, thus, to your Item Discovery as well). This is a good way to improve your character as long as you don’t care about looking a bit “corpsy.” If you get tired of that, use a Purging Stone and you are good to go for a while.