LDCad's own GUI system indeed looks not very slick. To be honest, when I was still using SR3D Builder a long time ago, I was a little hestitant to try LDCad, because it looked so strange on the screenshots. 
My point is, I have no problems at all with the GUI and it works wonderful, but I can imagine it might 'scare' users off.
In my opinion, something that would be really cool would be something like Microsoft's Ribbon Interface like in their Office applications, also a bit like Autodesk implements in their 3D software.
But, changing the gui is (again, in my opinion of course) far not as important as new features (or bug fixes). Because, well, it works perfectly fine as it is now.
My point is, I have no problems at all with the GUI and it works wonderful, but I can imagine it might 'scare' users off.
In my opinion, something that would be really cool would be something like Microsoft's Ribbon Interface like in their Office applications, also a bit like Autodesk implements in their 3D software.
But, changing the gui is (again, in my opinion of course) far not as important as new features (or bug fixes). Because, well, it works perfectly fine as it is now.