I'm pretty sure that serious Bionicle fans have all dealt with cracking of the joint socket pieces. However, is super-gluing the broken parts a solution? I'm worried that the joint socket won't be elastic enough for the joint piece to enter, or even that it might crack again.
Super-glue? Nope, no super-gluing if LEGO has anything to say about it.
This is probably a duplicate question, but if you contact LEGO directly, they will replace the part for free. Follow this older post for details.
The socket joints from around 2008-2010 were poorly designed. They were both too thin and too tight, so cracking was a very common problem.
Because the issue is the shape of the part, super glue doesn't do much. I tested it out on of my broken joints and the parts cracked again the first time I connected it. So don't bother with that.
What may help is sanding the inside of the socket's prongs down to make it less tight during insertion. I tested this out on a few of my sockets. Sanded sockets took 100 insertions without cracking while the ones that weren't broke after 20-30. However, I've also heard that the 2008 joints crack after sitting too long in a connected state, which sanding may not prevent.