Those are fine observations. You are right on the actual health and armor numbers. Kraken is very close to Goliath in health and armor (1000 points separate each), but if you didn’t see the values, you’d never guess it while playing. Kraken feels less tanky and doesn’t last as long in a fight. Why? @FrontlinerDelta is on the right track.
Kraken gets shot a lot more than Goliath does.
Vulnerability during attacks - Kraken’s powerhouse attacks (Aftershock and Lightning Strike) make him a sitting duck for many seconds at a time. He can barely move during these attacks. Aftershock is a two second build up. Lightning Strike is three, if memory serves correct. That’s a lot of time to soak damage. Especially if Hyde is melting your face. Kraken is most vulnerable when dealing the most damage to the Hunters.
Air target vs ground target - When Kraken is up in the air, he’s pretty easy to see. Even though he’s a smaller target, he’s usually facing the whole team, which makes him vulnerable to recieving damage from the whole team. Goliath on the other hand, is usually in the middle of the Hunter pack. When you’re shooting Goliath, he’s leaping, charging, moving around you. Kraken is usually fighting from one direction.
Mobility - Goliath has two abilities that can be used for increased movement - Leap Smash and Charge Attack. Kraken has NO abilities that help him traverse. This makes Kraken more vulnerable to Tranqs. Additionally, when Goliath runs, he’s leaping and going from ground cover to ground cover. When Kraken runs, he’s usually in the air, for everyone to see, getting shot in the back.
There is always more to the story than the numbers would indicate.