The motivation behind this change is to prevent the whales from leaving. Often, people who have completed all content are the ones spending most of the money in the game, so the teams objective shifts to retaining these players.
This is the strategy of mobile games, exclusively cater to the whales and ignore the majority of the player base. The hyper casual - casual players have left, now it’s the veterans, hardcores, and the whales left, and this change annoys everyone except the whales.
As well, this is incredibly short-sighted system. The expertise system is not engaging, it it just a laundry list of chores to increase your gear score. The expertise change removed build creativity, and locks people into specific roles. The new umbral system just reinforces the expertise system, with even more dailies and a tedious grind.
What happens when people reach 625GS? Will a new system take its place to grind to 650? What happens to all the new players who join? Will they have to go through the same grind that the hardcores and whales did? AGS will probably make gearscore increases easier for new incoming players, which will have backlash from the whales.
With the changes that make leveling crafting harder, changes to lower the amount of resources gained from nodes when players have the yield faction card, and nerfs to drop rates for specific resources it is clear that AGS doesn’t respect the communities time and work.
To me, this system is a grind put into place without a lot of thought, and will be made significantly easier when new content is released. The best course of action is to simply not engage with this new umbral system.
I am not going to complain and neglect to propose solutions. To me, people should not be logging on to grind, people should be logging on to have fun. Implementing rankings for PvP, duel arenas with rewards and leaderboards, dungeon speedrun leaderboards, tournments, maybe wave based arenas, and creating a server community is the best way of retaining players. Give people better methods of getting the gear they want, make nothing feel like a waste of time. Instead of a skinner box, make endgame events that are fun. The foundation of a good game are there, you can do it.