the issue is not "why did they go for it"
the issue is, why has McVay become Jeff Fisher in the red zone?
the problem is that as you get closer the end zone, it gets tighter. harder to run, harder to pass. the back of the end zone becomes a barrier from spreading things out.
point being, when you're some where around the 15-20 yard line, the plan should not be to inch your way closer for a first down at the 10. then try to inch your way the rest of the way in.
you need to take your shot(s) into the end zone while you can still run a regular play and stretch out the defense a little. so you take a shot from the 15. don't wait until your on the 4 yard line, having run twice, now facing 3rd and goal.