Why is D unpopular?

[Walter Bright]

The optimizer and backend date back to the 1980s, and were written in the C 
style fashionable at the time. I've been slowly refactoring it to be better, in 
particular use of D arrays, and the CodeBuilder system. It still excessively 
uses global variables, though I have refactored some of that away.

The frontend dates back to 2000 or so, and was written in the "C with Classes" 
style of the time. Of course, this is outdated today. It doesn't use templates 
because C++ templates of that time were terrible, and frankly, I still find them 
unpleasant to use.

A recent "D-ify" of it is the greatly expanded use of nested functions, and some 
lambdas.