Your comment hits on a lot of the points that motivated me to create homebrew-emacs in the first place.
For me, Homebrew is a pleasure to use. It's stable, robust, sensible, and has a great community around it.
ELPA, on the other hand, never seemed to have the same polish. Maybe with enough time and energy I could have configured ELPA to my liking. But that prospect never appealed to me when I have a perfectly good package manager I already use for everything else just sitting there.