I am still using MFC because I am retired, do this for fun, and I have barely learned MFC to date. IMHO, Microsoft comes up with a new language or must use product every few years to generate sales for the "must have" corporations. Otherwise, what else would they have to sell and what else would the Chinese have to pirate.
I am not familiar with C#; does it use pointers? I have been an engineer for almost all of my career and I find that pointers are the best way for me to visualize things, and are quite handy once you get the hang of using them.
I am sure that C# is a fine language; I hope for those using it that it is better documented than MFC, but then again it is a Microsoft product and I doubt it. Engineers also hate writing the documentation, but it is a necessary evil on any "good" project or product.