Personally, I would like to see more of creatures dropping items instead of just raw tria. I mean, seriously, what kind of rabid badger walks around with 10 tria (and where does he keep it?)?
Instead, the badger drops a skin, which can then be sold to either an npc or a player. The interesting thing with a system where mobs drop items vs. currency, is that it encourages more travelling and interaction. If they just dropped currency, then every day you would log on, go out and kill stuff, come back to town to buy more stuff, then go out and kill more stuff again. But if your loot consists of pelts, small weapons, crude armors, and various magical trinkets, you will need to go around to various vendors to sell your items for the best price.
It could also be a help to balance the game, to keep certain mobs from being over-hunted. Say there is a mob that spawns (not sure yet how this sorta thing happens yet) close to the outside of town. Normally, all people would do (at least the newbies) is just run outside of town and kill all of them, run the loot back to town, then go back out again. If a system was in place for mobs to drop items, then after a certain period of time those items would be worth less and less, because there would be so many of them drifting around the economy. Most NPC vendors will probably have a minimum buying price, but I think that it would encourage people to explore further out, where more lucrative loot can be found.