ASPNETCoreModule not installed with .NET Core SDK
ASP.NET Core Module is installed separately from the SDK
It's not true since the release of 2.1. I'm experiencing the same issue on Windows Server 2016. The module was installed on developer PC after uninstalling old versions / installing 2.1 a few times, but still struggling with the same issue in 2016. %SystemRoot%\system32\inetsrv\aspnetcore.dll is still missing.
ASP.NET Core Module is installed separately from the SDK. You can download the current version 2.0.0 here. https://github.com/dotnet/core/blob/master/release-notes/download-archives/2.0.0-download.md#windows-server-hosting
See https://github.com/dotnet/core/blob/master/release-notes/download-archive.md for a list of other releases.