I wonder where you got the idea I don't know how a defense computer works.
When you choose an example in which the defense computer was not meant to be useful, and then say it is useless (and therefore needs a boost), I do wonder.
I wonder also when those 8 structures you say are hurt have the time to heal for those 22 seconds.
If I recall correctly, the majority of rushes do not involve the entire alien team, especially not until sudden death. Even when the do happen, its usually because someone has managed to cause enough damage to give the aliens an opportunity they don't want to miss. Except for a full scale rush, the aliens will come in waves. This is the reason I consider the defense computer to be an asset worth having. You underestimate the amount of people that repair damage except for large rushes. It was not unusual in my 1.1 days for me to see a turret smoking, with a human camping on top of it, and no one bothering to grab a ckit. Minor damages that don't matter *right now* are ignored to add up over time.
If one would want DC to be useful, it should be like that extra repairer. Repairing say 2 buildings at a time with a higher repair rate. It could be set to repair the closest buildings first making it tactical where you actually put the building. Right now I have no incentive to destroy the DC because I know when I'm going for the RC those 6 hit points it heals won't matter. What I would like is for the DC to be more of a key building since it is the only one that is not.
When you're going for the reactor the defense computer is more than healing, but you know that. Even so, I'd rather have a slower repair rate by a defense computer than have you waste your time repairing, you're kind of a good shot you know. But why must the defense computer be a critical structure? Turrets are not key buildings individually, why should the defense computer be so important?
Now even so I'd like to see how the defense computer would factor into the balance as you suggest. Personally I'd also like to see what would happen of the defense computer's healing rate was just increased to 5 or perhaps even 7 hp/sec. But I think it really comes down to a field test at this point.