I was really fucking pissed that my Sailor Moon S and SuperS DVDs didn't have the next episode previews. Oh well at least I have my subbed VHS tapes, laser dics and region 2 DVDs that have them. But if it wasn't for that I'd be really pissed!
But yeah, it's part of the show. If I haven't seen the show before I ignore them, but if I have them I watch them.
I also hate when they cut out the opening credits. Sometimes they'll have like 7 episodes on a disc so they put the opening credits, then all the episodes together, then one set of closing credits. Well different episodes have different credits, assholes! Maybe I want to watch different characters.
Or for Sailor Moon S they had changing intros throughout the series where new characters were added as they showed up. The original intro has very little going on, but by the end we have ChibiUsa and a bunch of others pop up all over. The placements of the changes, sometimes with groupings of characters who appear in close enough episodes, sometimes when you know they're in it, sometimes when you don't, is very historically interesting when considered in the context of what people knew when this show first aired. Then the North American DVDs just put one intro for the whole season. Fuck those guys. Fuck them in their asses.