"Unnecessary padding" means adding extra and unnecessary details or information to something, which can make it longer or more complicated than it needs to be. Full definition
The story is so tightly - woven and so elegantly paced that adding more puzzles would just feel like unnecessary padding. (heypoorplayer.com)
At 90 minutes, there just isn't enough to sustain heavy interest without a lot of unnecessary padding, and that's just what we get for most of the duration. (qwipster.net)
At 2 hours and 20 minutes, the simplicity of the story is lost while the modern story machinations come across as unnecessary padding. (cinemixtape.com)