I feel like daemonizing Emacs should be the default. I can happily add random stuff to my init.el which causes it to take a little while to cold start, but I never see a cold start so from my perspective Emacs is instantaneous for editing a random file. I keep hundreds of files open at all times and never have an issue with performance. I just go through and prune my open buffers once a month or so, for organizational reasons more than resource usage.
If atom has a daemon feature that I never found, or one upcoming, I'd consider it again. Until then my workflow involves too many client closes for me to not notice the significant delay that atom has when opening a new file.