Actually, this should be fixed with the 10.12.3 Sierra update, for the Enhanced Edition (a different issue in Sierra will cause D:OS Classic to crash on startup, though).
For EE crashes:
Are you shutting down all non-essential programs (especially anti-virus) before starting the game? Firewalls have caused conflicts (generally on loading screens, though) and overlays from graphics tweaking/monitoring programs or chat programs have also caused issues.
Game Center has caused startup crashes, particularly in El Capitan.
Check for updated graphics drivers, etc.
Try pressing the Cmd key at game startup, and enable all the workarounds, if possible.
Try verifying the install files: in the Steam library, right click on Divinity Original Sin Enhanced Edition and select Properties, switch to the Local Files tab and then click on the 'Verify Integrity of Game Cache...' button.