That was probably removed for cost saving. Yeah, it would have been nice, but they wanted to reduce cost where possible.
Since the Gen2 Volt is not sold in Europe, they didn't put the turn signals on the mirrors (they aren't required in US). I do feel like this is a safety issue, and it would be nice to have them. I can't imagine it saved that much money, but, yeah, Chevy is famous for widespread cost cutting.