I get what you're saying. Go to any gym and the cardio section will be full. Full of people not really training for anything. Most aren't even sure if they're doing the right thing if their goal is to lose weight. And if they are there to improve cardiovascular health, they're not doing it in a measurable way.
But you're also kind of throwing the baby out with the bathwater. Not everyone is mindlessly doing cardio. I'd say 25% are doing it for a purpose of say training for a sport or using it as a tool for calorie expenditure to achieve a bodyfat percentage.
A few times a week I'll do a 20 minutes HIIT session on the bike or elliptical post weight training. By the end of that 20 minutes I've sweated up a storm and I'm spent. I look around and everyone is still walking casually on the treadmill at a 2% incline. They'll probably be there another hour and barely raise their heart rate. I think cardio is also a way of exercising where people don't have to get outside of their comfort zone.
To me, it's a very interesting topic, this old cardio business, to be fit means to be able to do the activities required, the measure of fitness is the time we recover (HR returning to normal) I think, if we follow a weight routine and it gets us huffy-puffy, then what more is required?
Will more cardio make us live longer, or eventually wear us down?
Playing a sport, well, that's what training is for, to prepare us for the game, why do added cardio, the body is one system, cardio, training and workouts use the same system.
for example; We have Fletcher, playing 400 games we had Hird spending more time off the field than on, both presumably train in similar ways, which could of been a mistake.