Ok, yeah, I'm removing the entire Star Wars example for now because it's likely not an example, because arguably none of the examples given were actually needless subplots:

• 1) all of these scenes were important to the plot. They're not detractions from the plot, the main plot just splits up four ways. Just because they weren't the most major aspects of the plan, or, in the case of the Padme subplot, just because they eventually were in vain, doesn't make them baseless diversions.
• 2) From what I can tell, this trope is not the same as padding.
• 3) The podracing scene is an important part of the main plot, because, y'know, it got them off Tatooine.