Mentioned in the stream, may have missed in my Stream recap notes - but we are looking to make some improvements to Co Op & Party mode in the future as Co Op and Citadels I believe are some of the last areas of the game that have remained unchanged since we went live.
We will also be releasing the Roadmap at the end of the week which will give everyone an idea of what we will be working on this year.
In the meantime, I had passed this feedback on originally - but when we are more focused on any co op/party updates I will pass this on again.