I find myself using Ruin 3 as filler to hold my bahamut phase (or Pheonix phase, if paired with another smn) til SL is off CD whenever I'm savage progging
It's removal would mean that they'd have to either rework how Bahamut/Pheonix works (right now it's tied to SpS which means that high SpS builds will invariably lead to you drifting phases over the course of a fight, heck after 2 rotation passes my phase is beginning to misalign and I need at least 2 ruin 3 fillers in order to keep things aligned) *OR* rework how SL works (tie it to SpS?... which would be kind of weird for an oGCD and end up with SL misaligning with other buffs.)

It's a really good buffer and to remove it would end up requiring a rework of other stuff, otherwise there'd just be a huge misalignment.