If you have not read Matt Asay’s article on Miguel de Icaza I encourage you to do so before reading the rest of this post.
Now, one thing that Mr. Asay seems to either a) forget or b) fail to recognize is that the concept of rapid application development (RAD), was pretty much completely non-existent on Linux prior to the Mono stack. Engineering a .Net solution for Linux desktops, Miguel and the rest of the Mono team has successfully brought RAD to Linux in a big way. Several of the more popular Gnome applications are Mono based (Banshee, Tomboy, and Beagle).
Until Mono, developing an application for Linux was something that took a lot of time, energy, and C/C++ code. While C/C++ are two of the more popular languages around, C# has picked up some massive steam since it came out and a lot of developers only code in C#. When you can increase the number of potential developers for your platform just by simply giving them the libraries and tools to do the development, that is a really big deal. That is why Mono is a big deal. There is a reason that Microsoft has not taken Mono out yet. It is because even they recognize the benefits of having .Net be cross platform. To say that Miguel’s talents are wasted because he is trying to bring a development platform that will increase the number of potential developers for Linux 10-20 fold, is ludicrous at best.
Linux needed developer tools that would allow people to develop software quickly and more easily then was available. With Mono, any C#/VB.Net programmer can write code that will work on Linux, and if they take their time they can have it be 100% cross platform. That is something to consider when making blanket statements, Mr. Asay.