I think weed is an issue where Biden's personal life experience and age show more than just about anywhere else. He's an old devout Catholic boomer that doesn't even drink and has a son that's had a very public struggle with drug addiction. I don't think he's ever going to exactly be a champion of legalization.
It's definitely something that can be criticized, but in the grand scheme of things, given that federal prosecution of marijuana "crimes" are basically non-existent nowadays anyway, it's a pretty small matter for me. You are right though that he has taken a step towards potentially rescheduling it, which is definitely a step in the right direction.