put it this way, lets say you have germany in qf, would you or would you not want Rooney who would be chomping at the bit to get out there and play in the squad or someone like Defoe or Crouch who can be described as ok at best
Rooney no doubt but if the likes of Welbeck, Sturridge etc. step it up and actually excel in the "Rooney role", then it would be harsh to drop them. There's also Rooney's history with international tournaments, he has always underpeformed in all the ones he's participated in.
but to not even have the option of Rooney on the bench?
Now that you've put it that way, yeah I'd definitely have Rooney on the bench. Like you've said, it depends on the group. If it's a group of death situation then the decision to take Rooney might be in vain.
It also depends on what happens between now and June (as in which players are performing well) and what Capello decides to do system-wise.