We did look at another looting system (in fact, we were one of the beta test sites for it). It was decided for several reasons that it wasn't a good fit for the shard, so we stayed with the loot bag system we already had installed.
For historical reference, the ability to use the loot bag is a relatively recent addition. For the majority of the shard's life the loot bag you currently have was turned off (i.e. there was no shard loot bag).
Having a gump that would pretty much cover anything lootable poses several issues. What is considered lootable by one player may not be by another. There are literally thousands of items on the shard. A one page gump has no way to account for all these items, so a multi page gump must be used, something you wished to avoid. This is the reason that the current loot bag lets each player choose what he or she wishes to have the loot bag pick up. If you want everything, yes your list will be long, but I don't see a way around that.
Ghost