The airline is understaffed right now. Tis not a good time to be a reserve line holder when we are understaffed. You're going to get used and abused. Worse, you're going to get revised out in the field and unlike line holders, reserves don't qualify for many disruption pays so you earn a lot less when they yank your chain.
And C2015 hosed reserve line holders by giving VTO holders with mixed lines (trips and reserve days) higher leveling. It means a reserve pilot will get called first and the VTO guy may never get called.