In a an work/purposeful communication it's a great feature not to have fun features.
People how love messaging are the bane of professional communication. You need to tell them to shout up, and tone down, but you want to do it politely. Just one person in a group that sends haha and gif to response to every message in a group is painful to deal with.
To summarize the great big problem with Matrix: It's no fun. No fun at all.