There is no sound notification when a message is sent inside a Team, like there is when you message a Group from Chat. The Banner and small red notification on the TaskBar is not enough to alert Team members they have a message.
People don't have a whole extra screen just for this app but if you don't have it open fully you will never see when someone is trying to chat with you. Before you say, but there is a beep keep in mind that if you have to use a headset then the sound goes there. Of course, who in their right mind would want to wear the headset for 8-12 hours a day.
At least with Skype, the icon on the taskbar would flash at you. Not perfect but better than this.
Agree, unless we tag all, you barely see a team notification-we find it easier to make a separate group chat - crazy!