It’s fair to criticize Biden’s lack of vision, among other things, but I’m skeptical that it’s actually hurting his electability. A couple interesting data points:

1. The Democratic Party is a diverse coalition, and the median Democratic voter is still quite moderate. Biden really isn’t too far to the right of the Democratic base on issues like heath care. He essentially supports German-style univeral health care rather than Canadian-style single-payer. Like the ACA, that would still be a significant improvement over the status quo, and has much broader appeal compared to Sanders and Warren’s M4A.
2. This election is really going to come down to a few states in the Midwest. Being able to capture less-educated blue collar Dems and swing voters in those states is key. Currently, Biden is polling pretty well there (Sanders isn’t too far behind, but far from a clear advantage).

Granted, there’s some risk either way. Clearly, a stale centrist like Biden is more likely to put off younger, more progressive voters, but I don’t think those voters are as crucial to winning back the rust belt.

I could be wrong, but I haven’t seen much evidence yet to support the new conventional wisdom on the left that says Biden’s moderation is a losing ticket. Obama won twice (and carried the rust belt states) on a fairly moderate platform full of flowery “unity” rhetoric. If ousting Trump is priority #1 (and it should be), we could do a lot worse than Biden.

And while I’m personally to the left of Biden on most issues, I take his point that a healthy democracy needs, at minimum, two functional political parties. Along those lines, I think the centrists and center-right folks who are at least trying pull the GOP back towards relative sanity are doing a valuable service. Even if the Dems become more progressive in the years to come, which seems inevitable, Republicans will still hold power some of the time.