Better graphics.
Models that look like something from mobile game are “better graphics”?
Terrain and trees that look worse than they did in the original are “better graphics”?
Lighting and colors that are all over the place (esp. in hero portraits) are “better graphics”?
Not being able to tell apart units during fights is a sign of “better graphics” in an RTS game?
FFS the hero portraits don’t even have proper speech animations… THAT’S "better graphics?
Tell me you are joking…
Stable framerate. Finally.
Is that why pro scene still plays in Classic mode, and people constantly complain here about performance issues? 
Single player. No more “online-only” for campaign and custom maps.
Comment in link below says:
“The game can only be played offline if it is periodically logged into Battlenet. If too much time passes, offline play is locked out until it’s logged in again.”
So that ain’t tru either
Improved campaigns.
Oh wow they added a few new skins/models! So what? How much stuff they removed instead? Even removed voice lines, that might seem… un-PC. And you yourself mentioned Custom Campaigns.
It’s a completely irrelevant detail. But irrelevant details (like footprints) are seemingly what they are focusing on currently…