you can kind of achieve this with yasnippet. I made this below:
# -*- mode: snippet -*-
# name: simple-link
# key: sl
# --
[[$
1.org][$1]
to use it, you type sl, press tab, type in the file, and then tab ], and you get your link. that may be better than typing everything out, if you remember sl for simple link, and press tab. I tried to not have the trailing ] typed in, but as soon as you type a character org shrinks the link and it does not behave as you want.
As an alternative, consider writing a short emacs function that inserts what you want.
(defun sl (link)
(interactive "sLink: ")
(insert (format "[[%
s.org][%s]]" link link)))
Now you type M-x sl
then enter the link in the minibuffer.
What you want probably isn't feasible. How do you differentiate [[foo bar]] from a file and a heading in the current file? Another customization variable ;)