I think it's also because it's the last season and the show-runners really don't have time (and maybe not the budget) to introduce another main character - Allison Mack's practically already moved on to other projects, so we'll just have Tess take over the Oracle role. We want Big Barda? We're already paying Cassidy Freeman, just add it to her character. And so on.She's got classic Late PC Syndrome. She joined the group a lot later than the others, and so doesn't have years of established history. She's got a lot of unresolved stats on her sheet, which she's filling up to tie her into ongoing plots as they go along. But it's a bit ridiculous.
"Last adventure, I was introduced as Mike's character's handpicked replacement to run his company. This adventure, I'll resolve my undecided d6 Relationship as Checkmate Owns Me d6. Next adventure - oh, it's about Darkseid? Cool. I can resolve my undecided d8 Distinction as I Was A Teenage Female Fury d8!"