We have WAAAAAAAY too many hostile mobs and they all do the same thing. Glow squid/Moobloom would add some variety in our passive mobs. Think about it this way: All hostile mobs are not real life things. They are not real. Iceologer would just be another Illager that isn't real. A moobloom or glow squid isn't real, so it would add a lot of variety in passive mobs. I'm personally voting for Glow squid as I think it would be interesting to have glowing armor, in Vanilla and servers.
So, in conclusion, VOTE GLOW SQUID FOR MOB.