1 - Most people want to run OSS...specifically Linux so they can leverage all the tools that run better on (or only run on) Linux. Like memcached, varnish, redis...Running .NET on Linux is silly.
2 - Want a dynamic language because it's more productive.
It isn't because it's "not cool". It's because general purpose languages are a dime a dozen, and there's no reason not to pick the best one possible. The only advantage .NET has is if you are doing work that integrates with other MS products.