The overloading mechanism should be used in place of optional parameters for several reasons:

* Optional parameter values are baked into the method call site code, thus, if a default value has been changed, all referencing assemblies need to be rebuilt, otherwise the original values will be used.
* The Common Language Specification (CLS) allows compilers to ignore default parameter values, and thus require the caller to explicitly specify the values. For example, if you want to consume a method with default argument from another .NET compatible language (for instance {cpp}/CLI), you will have to provide all arguments. When using method overloads, you could achieve similar behavior as default arguments.
* Optional parameters prevent muddying the definition of the function contract. Here is a simple example: if there are two optional parameters, when one is defined, is the second one still optional or mandatory?
