While a bit of the stuff in this thread is above my head / knowledge I entirely agree with this statement
Anything that makes things easier for the end user gets my vote. If that means being able to modify the looks, build themes without having to learn php can only be a good thing.
Of course (IMHO) the best means would be a graphical front end where you can make changes and then review them in near real-time such as in wordpress. Heaps good, and probably almost impossible to achieve. Such a thing, were it offered by any forum software, would drag many new users away from SMF (and others) in droves.
Why new users? Well I think many are initially far more concerned with looks rather than function.