The extremely simple syntax is underrated. When you are writing code in a language, at some level you have to parse it in your mind, to make sure the compiler will accept it.
When I first came across TCL after years of writing C++, I couldn't believe how much lighter the mental load was (I hadn't even noticed it until then).
I don't even play around with TCL anymore, but I've been writing Ruby for a few years, and it's been a good time. The syntax isn't dense enough to block out the constructs, I guess.
Anyways, I was looking at Dart a while back, and sat down in my editor and started working and quickly realized that I hold the entire program in my head but had to keep checking a cheat sheet for syntax. There's definitely something to be said for languages or tools that can alleviate that blockage.
I guess it's the level of abstraction more than anything. TCL is really neat and being that the syntax IS the code, like Lisp, there's really no difference between how a solution works in your head and how it has to be written in the editor.
When I first came across TCL after years of writing C++, I couldn't believe how much lighter the mental load was (I hadn't even noticed it until then).