Brutally honest? Lol man cardio isn't bullshit and neither is running on a treadmill. One of your pros is: "some people just like it." It builds your cardiovascular endurance, which benefits your heart? That doesn't sound like bullshit to me. I'm not a runner so I don't know if it inherently ruins your knees, but I know that a lot of runners have been doing it for years. This leads me to believe it's form as opposed to anything else.

TLDR: cardio is not bullshit.