An object manipulation trick can be interesting for many reasons. This is an attempt to list some, so we can understand them better.
It looks like this trick is hard.
You could hang this on the wall.
It means something, even if that something is abstract.
Novelty or surprise
You had never seen or expected that before
You had seen or expected that
Why are these reasons interesting? They each deserve a whole post for themselves..
All these can make a trick interesting to watch. Pushing tricks
further in one of these directions might improve them. Of course this
theory can be applied to routines too.
Interesting to watch is not the same as interesting to do.