I get very little joy looking at tropical bonsai........because i dont live in the tropics.So therefore they look most untree like to me,and quite often very "samey"Bonsai can be very personal. Some of us prefer different stock. Saying if you don't want any of those dont bother doing bonsai is like saying if you dont like peperoni don't eat pizza. Everyone likes what they like. I personally love Tropical bonsai. If everyone did it the same way there would be no room for new things.
At the end of the day poor material is poor material,95% of these are excellent material,dont forget one man's finished tree is another man's unstyled tree,it's all a question of refinement