This is like moving from the
Ant DSL to a stripped-down version of
Groovy/
Python. Yes please.
Speaking of layout, some combination of RCX Code (image below) and NXT-G (picture even lower down) would both be pretty simple and fast to use, and pretty powerful. However, if that isn't possible (or isn't popular enough to be justified or making it look good would be too much work (as you said)), then my vote goes to text-based with somewhat Python-ish syntax (or M's on the bottom of page 1). With that comes, of course, a big need for documentation, since having it purely text-based can be a bit off-putting for newcomers.
RCX Code:
NXT-G:
The wires are basically the NXT-G equivalent of local variables, and the wire colour tells the data type (bool/int/string). The briefcase blocks stores/loads the data from named variables. There is also a similar block for file I/O (SaveVariable/LoadVariable).
Oh, and custom blocks (functions; these are present in both versions too):