I think a lot of folks value having their apps 'fit into' their OS. For me, I see the constant churn in desktop OS patterns as tiring and essentially useless. Emacs provides a wonderfully consistent interface no matter where I run it. I can see how it seems foreign to others, but it is consistent. For me, that's a fantastic trade.
Yes, but eons have passed, things are different. Should everything else mold to Emacs or should Emacs fit into the overall OS/window manager/etc.
Maybe Emacs really is supposed to be an OS. I'm now wondering if there's a way to boot straight into Emacs. Clearly we could have a slimmer kernel /loader for that. :-)