I believe that Google sees Gmail as the primary app that people use and are rolling the other one into it. One is much more likely to keep a Gmail tab open all

I believe that Google sees Gmail as the primary app that people use and are rolling the other one into it. One is much more likely to keep a Gmail tab open all day long than a Google Voice one, so it makes sense to have it in Gmail. Note that it integrates with Google Voice: the outbound calls show up with your GV number and inbound GV calls can ring inside Gmail. I would be surprised if ultimately GV is not completely inside Gmail.