Hopefully they're never a guaranteed item.
a while ago, i would have fully agreed with you. i still do, for the most part.
if they are going to continue releasing them in spinners, events, etc, then just put them in the IS. if not, then never release them again.
either take the cat all the way out of the bag or shove it back in and zip it closed to die and rot. personally, i prefer the latter.