I mean look at Multiwinia, one of my favorite games of all time.
No base building
No resources
Barely any need for in depth unit management
Units consist of entirely the same models. (which arnt even models really, just 4 pixels stuck together)
It will be good for the fans. All the haters will just find something to hate more and blah, blah, blah like their opinions matter. I don't get why people think they could have done a Flood campaign though. All you would do is zerg rush the entire time without any strategy. A covenant campaign would have been cool, but a Flood campaign would be unreasonable. You can bet the score would have been at least a point higher if they had a covenant campaign with it.
The Co-Op sounds fun, but if your partner isn't a total idiot when it comes to "strategy" RTS games and not "zerg rush" RTS games.
Now we will have to see what DLC will become available for it.