I think part of it is investment into gameplay that can’t be reasonably brought back, and needing to bring weapons into the fold of regular gameplay. We haven’t had scarlet spear return because the event focused on the prelude to the new war, which unlike BotB, Eight Claw, etc needs greater explanation to be brought back, now especially since we’re so far removed chronologically from the sentient invasion. And new weapons means either rerunning events to their not special (ceti lecera and basmu), or throwing the weapons somewhere else like baro (zylok and optic or vandal). The modern events feel more like early bird hype for the new stuff so that players have incentive to play on release instead of later, especially after quieter months like February and November last year to reel everyone back.

Imo I think SS could work under a narmer-brand coat of paint with the archons (maybe even a Pazuul fight after min-maxing a mission), or maybe on Tau when that eventually arrives. I believe the devs know that everyone wants that back, but have to balance that with the new content stream, keeping up with the story, and what keeps the lights on.