I could care less about your disappointment with the weapon; and I am positive majority of ppl did not finish all 5 sets and even if you did, there is a lot of time till next content to make 2 new gold accessories and sell/trade other to other players
Having to redo any items in your gear to adress any changes made to them is connected to losses for the player, you can not expect to be able to sell the "old" pieces for exactly their cost.
Making any changes to those items now and forcing active players to redo their gear to keep it optimal kind of punishes them compared to those who did not invest as much time into the game up to now.
So all items should be final in their state when implemented/acquirable in the game, except there is a grave need for balancing purposes. Otherwise I see no reason why any changes should be made to items and I dont see such reason in this case.
Every player should be thankful to be able to grind inis for 2 items less to have the optimal gear, the only point I see and as you pointed out yourself, is wanting full golden/ultimate gear for aesthetics, but then you have to deal with suboptimal performant gear.
Simple choice imo.
So why make this even a topic here. If devs were aware of this, noone is at any disadvantage. If devs were not aware of this and chose to do nothing about it, noone is at any disadvantage. If they decide to change items now, just because not everyone is going to get 5 ultimate accessory pieces, many players (those who already finished gear and those who now will have to grind longer to complete their gear) will be at a disadvantage.
Additionally here is another rather fun fact, not really connected to the previous topic, but since you mentioned:
...there is a lot of time till next content to make 2 new gold accessories...
At multiple times and occasions the publisher and the dev team pointed out, that the ultimate gear should not be considered the "usual" gear for this content, but something extra rewarding for the very active players and that not everyone is supposed to be aiming to complete this ultimate gear, but "only" the red one.
Why this indeed was a very unhealthy approach I also already pointed out at multiple occasions a long time ago.
Now my point being is:
As the most active players are done by now with their ultimate gear and more and more less active players are following in completing it, I am wondering if we are soon to expect new content with new and even stronger sets of gear.
Otherwise, if the majority of players running rofl completes this gear, the whole original idea behind the ultimate gear would somehow miss its purpose, wouldnt it?!
I really am looking forward to a publishers statement concerning this issue.
Cheers!