Team Simple mode/Full mode
Suggest Teams will have the possibility to toggle between simple mode (just for chatting purposes like skype for business) and "full" mode to show full features. Microsoft Teams becomes like a small SharePoint system with chatting capability which is a cumbersome combination to achieve a basic chatting and file exchange services.
The simple mode will help migrations from SfB to Teams, as not all people within Organizations need the full mode at start. Today many companies fear resistance and stick to or still move to SfB.
Sean Ellis commented
Closely related to the #1 UI request - https://microsoftteams.uservoice.com/forums/555103-public/suggestions/17408641-please-create-a-professional-compact-chat-layout
Please also vote and support.