I think to have emacs work with today's web dev needs out of the box
is one of the most important need for emacs.
(see http://xahlee.org/emacs/modernization_of_elisp.html )
Even for working with pure static html pages, emacs's default html
mode is quite lacking.
The default html mode in emacs 22 (released in 2007), is at a level of
~1998's commercial html editors. (of course emacs has redeeming
qualities, i.e. its elisp system and all, that keeps us still sticking
with emacs)
Web development is my primary area of expertise. I have to work with
html mixed with css, javascript, php, perl a lot. Fortunately, lacking
proper syntax coloring isn't much problem. (after all, 99.99% web
pages out there are so badly formed)