Why would they put filler on an album they said they already had too much content for and paid for the recording of? Haha. You just dislike the songs, although I agree there are some weaker moments on here.
I don't think bands ever really think what they're doing is filler. And yet filler happens. Sum 41 ending up spending their own money to record two songs that they felt strongly needed to be on their last album. Guess what, those were the two that felt most like filler. I guess people do use that to decsribe things they don't like, but in Sum 41's case they really ruined the flow of the album. That's when something really does feel like filler.