Yeah, I actually agree with you that using carriers to soak up 2 hits in a battle does seem ridiculous. After all, carriers are capital ships and one SHOULD be protecting them, not throwing them in as fodder. Unfortunately, this is a tactic that I often find myself using, particularly as USA because of their greater income can more easily replace the carriers than other nations. Many times I have sent a fleet into a large battle and rather than taking hits on pieces that can still shoot the enemy, I will take a hit or two on the carrier.
This usually happens in two cases:
1=the first round of US hits didn't go so well and there are still a lot of enemy targets to destroy. In these cases, I usually intend on taking the planes that would have landed on the carrier as future casualties because I know I will be getting more casualties in the 2nd or 3rd round of combat.
2=the attack is taking place adjacent to a friendly territory, in which case I know my planes will still have a landing space. Also, there will still be many enemy targets going into the 2nd round of combat.
So, while it may not be a sensible tactic, nevertheless it is one that I often find myself using.