ember-cli is such a vast usability improvement that you would be hard-pressed to find a single developer who's tried it and would prefer not to use it.

It's in-line with Ember's whole philosophy: anything that we can solve once together in a standard way, we should. Most of the time you are not a special snowflake and you can benefit from the same build stack as everybody else. If you need more, ember addons expose a standardized interface to sharing whatever feature you need.