When it comes to design, C++ is a good example of why having a benevolent dictator is better than a committee. I still think it's a huge mistake to not have a standard ABI and rely on C's ABI.
It would definitely making interop between C# and C++ much easier. It would make interop between C++ and any language much easier. The only way to do it today is to extern "C" everything. It's ugly.