Adobe's Bracket front-end editor is open-source, yes, but does it have any traction? I have yet to hear any front-end developer friends who even bother to use it in any capacity other than testing it occasionally. I tried it a few times and couldn't justify why I'd want to use it over Sublime Text.
Historically, it appears that closed source front-end editors like Textmate, Sublime Text and others find more success and usage in the market than open-source front-end editors.
Historically, it appears that closed source front-end editors like Textmate, Sublime Text and others find more success and usage in the market than open-source front-end editors.