Just out of curiousity, why are those methods so bad?

Because a queue is a very simple concept -- you put things in one end and take them out the other in the same order -- and the addition of those methods broke that simple model.

The fatuous addition of those methods removes all the guarantees associated with the well-proven abstract data type, rendering it a hybrid mess that is impossible to correctly reason about.

It turns a queue (back) into an array -- when the whole purpose of the module is to turn an array into a queue!