One replies: "Microsoft shouldn’t (and doesn’t) hire people that have specific skills; instead we hire based on that person’s growth potential". Personally, I don’t agree with him. Hiring by growth potential is only applicable to campus hire. Not applies to industry hire.
In "Monday Morning Leadership" (Chinese version), the book I just finished yesterday, it emphasized that we should only hire right people. After being employed for 3+ years, I realized that it’s very true.
In this case, if C# is the working language and C++ is rarely used, why we hire a C++ expert and let him study C#? It doesn’t make sense to shareholders. We should hire a right people (who is a C# expert and has a little C++ basis though).
In another book, titled "Now, Discover Your Strength" (Chinese version), it also emphasized that company should have employees do what they are good at and it’s waste of money and ridiculous to hire an expert on Stuff A and training him/her to be an expert on Stuff B.