Cassiopeia flash ult interaction vs Gragas body slam

I'm annoyed after hearing that riot thought it's OK to have gragas body slam flash combo be fair and fiddlesticks ultimate Zhonyas (don't actually care about this one it's just another example) but Cassiopeia had to lose her flash ult interaction. It's not even as strong as gragas s body slam flash because while you're trading a powerful spell for a guaranteed hit Cassiopeia s ultimate stun isn't a guaranteed hit. And it's an ultimate ability mean while gragas doesn't always need flash because he has more mobility and crowd control to escape sticky situations. While Cassiopeia only hard crowd control is her ult.

EDIT: i forgot to mention that i dont want cass to have it and gragas not to. i want either both to have it or this kind of stupid interaction removed completely. another point is that i think they just needed to make the cass ult effect appear properly.