Well it gives the Ina Actress a way to participate in the show Sans Make-up. Sometimes it can get tedious to go through 4 hours of makeup for what may become 30 seconds of screen time. Why I think there should be some "Levels" of make up. Extras and Hallways aliens shouldn't have a high level of detail, maybe just a quick rubber mask. so maybe 1 hour instead of 4 hours in the chair.
As for the Red Shirting, I was on that train when they introduced her, and when Tilly said some might not make it, I was like.. yep new girl is dead.. until she wasn't. Wasn't hoping for a death outcome, It was just Telegraphed Hard.