I did too. Taskwarrior is just so streamlined for todo's. I always felt org-mode was pretty clumsy at that, in comparison. But maybe I just don't know org-mode well enough. But that itself is symptomatic of what a steep learning curve org-mode has to take full advantage of its more adavanced features. Taskwarrior was much easier and quicker for me to learn, and has a boatload of features to rival org-mode, as far as task-oriented features go.
I do wish Taskwarrior was fully integrated in to Emacs, as org-mode is, but that's the way the cookie crumbles.
2) Memory use that'd melt my rather old daily-driver laptop.
3) A community of /cool/ people that make web pages that appear blank on my browser (xombrero + js whitelisting).
4) Some <insert latin prefix here>pilers, e.g. CoffeeScript, TeaScript, Dart, Soccer...
5) Minifiers, maxifiers, maybe even identifiers.
...
Elisp certainly lacks two things that are real pain points, a well-performing vm, and proper multitasking. I'd also like to have a good way to embed webkit/gecko into emacs, that'd give a lot of possibilities.
That's actually equally lacking on JS side (if you mean parallelism); moreover, Node advocates callback/promise-based concurrency, which is completely achievable[1] and even practical in Elisp, too. There are at least two HTTP servers written in Elisp.
Lack of a high-performance VM for Emacs Lisp is a real pain, though. Emacs does everything I need it to do, it's just that sometimes it's a bit slower than I'd like.
I wonder why the atom org-mode package is not more popular ... The power of a desktop js editor with org-mode capabilities would be awesome !