I think if that is how you want to describe him, sure, sounds great. But he is still a former Representative with only 4 years experience. When considering him against even a junior Senator such as Kamala Harris, it's tough to justify why he should be the nominee over her, let alone someone like Joe Biden. Beto would be a fantastic pick as a Vice President for the reasons that you listed, I just don't think that he is the most qualified nominee for Democrats to run, no matter how attractive the idea of him (or just he in general) is.