@metawhy said:

The big difference I see between these two bands is the difference between Robert Hunter and Tom Marshall.

Big difference.

This is definitely important. One way of illustrating this: 'Backwards Down the Number Line' is a song entirely about itself; there's no metaphorical content, no twist, no imagistic connection to anything but Trey and Tom's relationship. It really is a birthday card, sung. Can you imagine Hunter writing such a purely straightforward, informational lyric, and the Dead playing it straight?

I admire Trey for being willing to do confessional stuff like Joy, BDTNL, 20YL, Light...but yeah, Marshall isn't anywhere near the lyricist Hunter became.