In my opinion, dynamic scope is adequate solution for Lisp approach, i.e. expressive power on the first place. Newlisp is very simple and expressive dialect, and it is pleasure using it. Dynamic scope allow some things statical scope doesn't. Sure, the price for that expressive power is that one has to be more careful, but this is not really that hard, and it shouldn't be the problem to anyone who really accept basic Lisp ideas.

I can see how dynamic scope - just like dynamic typing, eval or macros - could be seen as problem for people who want language like, say, Ada that puts safety on the first place. It is legitimate position. But it is not design goal or tradition of Lisp. Lisp is designed for AI, exploratory programming, hacking, expressive power, adventure. Owner of this site, Paul Graham, frequently wrote in that vein. It is simply not consistent to brag about expressive power of Lisp, and then turn into safety freak when one mentions dynamic scope.

OK safety freak is maybe too strong, but you get the point.