I can understand the disappointment, but the reality is that ASP is a dying language. It is being replaced by ASP.NET which Dreamweaver CS4 and beyond does not support.
Microsoft has done nothing with Classic ASP since 2000. Sure, Newer versions of IIS Still support it, but that will likely not be the case forever.
We moved to PHP support so that we would be able to offer more robust extensions with a a greater feature set. Developing extensions to work in 4 server models caused us to have to scrap certain features that we would have liked to add because it was not a possibility along all 4 server models. By focusing on PHP, we can focus our efforts on features that are possible in PHP.