The most common IDEs are Visual Studio (Microsoft), Xcode (Apple) and Eclipse (open source). A toolchain is basically a set of applications to translate source code to something the machine actually understands and consists of compilers, linkers, assemblers, build systems, debuggers, profilers and the like (often hidden behind or part of an IDE). The most common toolchains are the one integrated in Visual Studio, the one integrated in Xcode, and the stand alone GNU toolchain (open source). For Wii U, Nintendo decided to go with the GHS MULTI IDE and toolchain, a rather exotic and expensive suite that is typically used in high reliability, high security embedded development (like medical, industrial and military applications). It's simply not a familiar environment for game developers, most of which most likely never even heard of GHS, which means that it requires additional training and education.