And as I said, they just try to be informative. Hell, you might enjoy Retsupurae. It's a series with some SA members who basically watch and make fun of bad let's players since they hate exactly what you are talking about. They got a lot of flack for their video making fun of Pewdiepie, pointing out those exact same issues you have with Let's Play.
Youtube has sort of ruined the image of Let's Play, since they kind of just took the word and applied it to anyone playing a game with commentary.
If I was playing a game and wanted to show to someone, I wouldn't just sit there silently as they watch me. I'd interact with them, maybe joke about something or point out bits about the game. I'd want to be informative, and not just a silent stone playing be himself as someone else watches.