Why Develop on Wss 3.0 and MOSS?

Many people were asking me this question and i came across somthing that might help on that :

Why Develop on Windows SharePoint Services?

Web Parts

We put a modular user interface into every SharePoint site, and it uses the full power of ASP.NET and Visual Studio .NET.

Sites as Programmable Objects

SharePoint sites, their contents, and the servers that deliver them are accessible, manipulable, and extensible via a managed code API and a set of Web services.  You can even package them up as Templates to deploy reusable solutions.

An accessible, extensible content store for documents and other data

You can reach the contents of a SharePoint site via Web services, WebDAV, or the Windows XP Web Client service.  Office applications read/write from/to SharePoint sites -- your application should as well.

Why Develop on SharePoint Portal Server?

It's based on Windows SharePoint Services

If it works in a SharePoint site, it'll probably work in a MySite, an Area, or a portal home page.

Extensible services

For indexing and search, people and personalization, and content aggregation/organization.

Enterprise Application Integration

EAI features, particularly in the areas of Single Sign-On and BizTalk Server interoperability.