FYI: Attribute tokens are NOT able to be looted from other avatars, nor are they able to be traded.
To address the issue raised in the opening post-- One of the reasons the attribute token system was implemented was that it provides much more flexibility in the awarding of attribute rewards for completed missions.
Due to -very detailed and quite boring- technical reasons related to the way the mission system works and the way attribute points are handled internally by the engine, the mission system is only able to award a single attribute point for completed missions. This means that not only is it not possible to award 1/2 an attribute point for a mission, nor is it possible to award 3 attribute points for a very difficult mission.
The new attribute token system addresses both of those limitations, and allows partners to create missions with (fractional) attribute rewards for relatively low-level creatures which do not qualify for full-point attribute rewards under the mission rewards guidelines.
A nice side benefit of the attribute token system is that it also gives players the freedom of deciding when to redeem the attribute points earned, a flexibility which many players seem very happy with.
Unfortunately, the limitation described above also applies to the attribute token NPC, which is actually no different than other mission brokers. This explains why the only option offered by the attribute token NPC is that of exchanging 100 attribute tokens for 1 attribute point.
I'd have to check the database to be 100% sure, but I am fairly certain that no player has completed every single mission that awards attributes on each and every planet. If you have a stack of attribute tokens smaller than 100 units, it is very likely that you will be able to find an uncompleted mission somewhere that will allow you to bring the total to 100 and redeem your attribute point.
Also, new missions are being added regularly by Entropia Universe planet partners. For example, Calypso has several new Iron Challenge missions in the pipeline for the next partner release, and you can expect similar missions from the other planet partners.
In other words, there is little to fear that you will ever be stuck with "leftover" attribute tokens for very long.