It’s categorically not padding, you’re right…
What they were, back then, was ludicrously experimental. They were messing about in praccy rooms and just creating all sorts of mad stuff. Spiders and Tin Planet are actually full of tracks from Tommy (which includes most of the hits), but also tracks from lead-guitarist Jamie Murphy, and lots of input from other members of the band like Franny, Yorkie .etc
Single releases invariably came on 2 cds, which usually meant 2/3 b-sides and a host of remixes. There’s tons of other tracks that never even made it to being B-sides. They’ve never been short of material, so there’s been a case of churning stuff out to “fill and album”…
That said, obviously, whether we like something or not is personal taste… but yeah… they’ve never cranked out anything for the sake of it. This last album has taken since 2012 or something, for example.