  C++ has an astonishingly complicated grammar, which means that compilation takes forever and other tools don't work as well as they do for languages with simpler grammars, like C or Java.  C++ doesn't really have compile-time encapsulation: if you add a private member to a class, you need to recompile everything that uses that class even though the class's public interface didn't change. That woudn't be so bad in and of itself except that C++, again, takes forever to compile.  C++ also doesn't have run-time encapsulation or really any serious run-time error checking that you don't do yourself. Yes, it's for performance reasons, but some people are working on problems that aren't performance-critical and would prefer a language that doesn't pound nails through our dicks. (if it doesn't have encapsulation, why do they call it "object oriented?")  