If you are trying to move keys around, but only in emacs, then it is probably easier to use a translation keymap.

    (define-key key-translation-map "[" "{")
    (define-key key-translation-map "(" "[")

As far as the binding to `skeleton-pair-insert-maybe`, I don't see this being setup to any key. You can use the code https://emacs.stackexchange.com/questions/653/how-can-i-find-out-in-which-keymap-a-key-is-bound to find the keymap,and then use `(define-key keymap "[" nil)` to unbind it from that keymap. When you want to unbind it depends on where it is being bound!