To be fair, only very large text files trouble Atom. And when does any dev ever actually open massive text files in text editors. I'm a Vim guy and have only briefly tried Atom, but I still wouldn't dream of opening a huge text file in Vim, even though it would cope a lot better than Atom. If it's a log file or something I'm going to be using tail/grep etc. to deal with it.

Yeah exactly emacs is hackable if you want to write lisp, which has a very small audience. So sure there is absolutely a desire for an editor written in a 'nice', hackable language like Python or JS (forgive me JS haters) to prosper.