Last time I noticed, clowns don't perform anything similar to freestyle, jugglers do. Well, I respect your opinion to prefer one style, but I never tried to change that.
As far as your advantage for lowers goes.
Cardio: Well, pretty much any freestyle is good cardio. Only sitting isn't quite as good, but it's great core exercise. Also, the act of transitioning from sitting to standing is probably the most intense workout you can get in freestyle. It requires the most energy.
Dog poo: Well, I am pretty sure there are places you could train this without it. Poor joke by the way.
Looks better: That's your opinion, and I respect that. I never tried to change that.
Now for why I prefer all around
1. I started as a footballer, and I like being able to control the ball with all surfaces of my body. The feet standing is the most simple form which I had already mastered before beginning freestyle. I learned basic control with all body surfaces and sitting before I progressed to learning tricks.
2. Looks better: I think it looks better to do a bit of everything. I prefer seeing things that surprise me, and all around opens far more avenues.
3. Like I said, all freestyle is good exercise. There are actually uppers tricks like back or chest juggles that are more intense workouts than lowers, because they use larger muscle groups.
Any circus juggler that has done anything that can be compared to any type of freestyle has also done basic lowers as well. The difference is football freestylers specialize in only the freestyle tricks, so we master more advanced tricks in all areas. Obviously, lowers is the most popular area. It's more natural to juggle with your feet standing, and most people's first tricks for atw or cross. From there, it's only natural to improve this area and enjoy it the most.