Because of the attrition in GW, healing is key. Barriss is the best HoT plus a health boost. It was a reasonable question. She isn't NECESSARY, but if you are having trouble, she helps a lot. Luminara is a viable sub. HoT counters attrition.
If someone dies, and it is not a suicide squad, retreat and either swap toons slots or make different decisions. The only battle I allow an A teamer to die in is the last one.
Development budgets are not intrinsically linked to profit margins. Development schedules in corporate environs are typically pretty slow. This is a niche phone app, and likely has a very small budget and staff compared to, say, Madden 2015.