A .NET content deployment module would be a very welcoming feature. This would have two main benefits.
1. The entire Tridion back-end is .NET. (Here I consider the content deployment module a back-end module) . Consistency in technology makes things easier to work with and to maintain.
2. A .NET content deployment module would invite many more people to build custom content deployment features.
Personally I am a .NET developer. I have always wanted to build custom content deployment extensions. However, with the current Tridion content deployment module I'm forced to use Java to do customization and Java skill is something I don't have, unfortunately. Building a custom deployer is therefore no option for me.
I think there are many who are in the same boat like I am. The number of Tridion .NET vs Java open source, and the questions asked on Tridion Stack Exchange do suggest this.
With a .NET content deployer Tridion would tap into a much bigger development audience, which is a good thing. It would be beneficial to both developers and Tridion. New ideas will emerge from this, no doubt.