I definitely agree with this. To be honest, when I first started playing the game and got one of these letters, I spent a considerable amount of time trying to figure out what they were. Intuitively I thought they must trigger some sort of quest, but over time I realized they were just junk. Considering they are confusing to new players, I vote to just give them a junk value or to change them entirely.
Also, I think there are other items that could stand to be improved. Currently, I no longer have ANY need for most staves in my party. Maybe somebody can point out their value, but items like the Staff of Incineration are useless on heroes because the initiative hit is just too much. I want my HERO mages casting their spells as quickly as possible, so I'll just equip the mage with weapons with initiative bonuses, or staffs like the caster one that have no initiative hit. Even the rarer ones that give 12 attack are not useful on heroes because of the initiative hit. If they didn't have an initiative hit I could see equipping my hero mages with them so they can get in some attacks once in while when they aren't casting.
The fix to staves is a bit tricky at first glance--we don't want to remove the initiative penalty from them because some of them are staves that we can give units. A trainable "mage" unit that has no initiative hit would be very powerful. Instead I think the easiest fix is to give the Mage hero class a benefit, namely, that they suffer no initiative penalty using staves. That makes a good deal of sense to me. You could also tie this to a trait, but I don't think that is necessary. This would suddenly make staves a lot more useful to Mage heroes.
At the very least you could make sure none of the rare loot staves have an initiative penalty. These would only be equippable by heroes, so it would not be unbalancing.
