I do care a lot about character development. I think it just doesn't bother me so much in season 5 AtS, because while I think it's off, it catches the aspect I think is more important (Spike no longer in hot pursuit to the exclusion of all else). Granted, it's implausible that he buys Buffy dancing in Rome (and her complete unconcern about the resurrection of her dear friend) -- but most of us went with that until season 8 retconned it, so Spike's not the only one.