There are a few very compelling reasons to move to Office 365, and in my opinion, Office 365 Groups are at or near the top of that list. Office 365 Groups combine resources from across Office 365 in ways that are not possible on-premises to give end users interesting new functionality.
Originally, Microsoft envisioned Office 365 Groups as resources that did not need much, if anything, in the way of administrative control. The idea was that end users should be able to control their collaborative experience without pesky admins getting in their way. This, of course, is a ridiculous concept that Microsoft has since corrected. Now Office 365 administrators have the controls necessary to ensure Groups are being used in accordance with organizational data usage policies within their Office 365 tenants.