I don't see how you could ever be stuck with the direction MM.Net goes in. If it changed significantly you can always choose not to upgrade and you have all the source code to maintian yourself if you like.

If a developer like myself, having little .net experience, wants to write a really robust commercial application that uses a database and have it be flexible and scalable it would take many hours of research to be able to build the framework for that application. MM.Net allows me to build a commercial application without all that research. Sure I might not have learned as much as I would have rolling my own but why would I want to learn how to write a flexible data access class when it only needs to be written once.

The other benefit of using a commercial framework is you have many, many users testing the framework in other applications built on that framework.

The .Net framework itself is a commercial framework. IMO, all Kevin has done is give us features now, many of which will eventually be in the .Net framework. For example two-way data binding in MM.Net now will eventually be a feature in ASP.NET out of the box. I think you could say Kevin is making the .Net framework what it is supposed to be and what it will be eventually.

Using a commercial framework that you have confidence in allows business and developers to focus on what makes money, business rules. This has always been the intention of .Net, Kevin is just helping it along.