They just need to make FATEs scale higher than they are. Currently, no matter how big the zerg is, the HP of the FATE mobs caps out rather low, making it nearly impossible for some people to get credit and impossible to get credit if you're not very nearby the FATE when it spawns.

As for the OP's point 3: FATEs aren't meant to teach you how to party. That's what the mandatory dungeon runs are for. Also, once all the people who aren't going to subscribe at the end of the free month leave, there will be a significant drop in zerging.