Our management console (the client) is integrated into MMC, so it's limited to running under .NET Framework. While e.g. StreamJsonRpc can be used in this environment, it would also result in an awful amount of dependencies (Nerdbank.Streams, Microsoft.VisualStudio.Validation, Nerdbank.Streams, MessagePack, etc.), all of which are kind of tricky to bundle.
So we decided that in the long run, a simple custom IPC implementation would actually be more maintainable.