Is the Glow Squid Useless?

They're a very rare sight to see, as they only have a 5% chance of spawning within a new group of glow squids. Killing them is useless since, like most baby mobs, they won't actually drop any resources apart from a few measly experience points.

What is the point of the glow squid in Minecraft?

The glow squid drops Glow Ink Sacs that can be used to brighten writing on signs and can be crafted with item frames to make Glow Item Frames. These glow item frames are brighter than the original, and will make whatever item that is being displayed by the glow item frame brighter without adding to its light level.

Is glow squid getting removed?

Mojang Studios has removed the glow squid for now, but it'll return in a future beta. In the meantime, any glow squid items have been removed from players' games. On a smaller note, Minecraft's support on older Android devices running Android KitKat (4.4) or older is ending with this beta.