As far as items are concerned, i'm more interested in getting something new, or special, relevant to what you are killing. The gems are fine, even if you only get one or two, it is still something that you can only get from killing a crimson dragon. The reward has no use, barely any difference from other gems and probably doesn't sell for much, but for me I love them because they are different and signify the killing of a specific "thing".
As poor as some of the mods i've seen have been, the new spellbooks and the coloured armours are also great, from the invading force, as they just look different from other stuff. I think I just like to hoarde and collect stuff in general, though. But a crimson cinture... being in factions gives you one that is better than a regular drop one, so why bother with the regular one which you could sell for heaps more. Unless you aren't in a faction, of course.