We seriously COULD use another Maokai considering he's the only tank that's seen any consistent use in such a long time. More importantly, ignoring any balance issues they may have, you just described a lot of tanks you know.
You have those with deceptively high DPS like Zac and Amumu with their ability to dish out non-stop stream of reliable damage thanks to their % damage. There's Sejuani who is pretty scary if her enemies are stupid enough to let her get to late game unimpeded. Rammus' Passive and his thorns makes him deal particularly high damage. Sion with his Q (if it hits) and his Passive. Braum whose Q hits far harder than a Support should hit. etc.
With the exception of Zac and Amumu who are specifically designed to inflict strong DPS if left unchecked, all other tanks are capable of dealing pretty high damage, even higher than Maokai even. They just tend to be lacking in the DPS department.
The tanks who deals little damage are the exceptions to the rule.
Because they are tanks, I personally believe that tanks should be CC heavy, but NOT do heavy amounts of damage. That is why I agree with him having more tankiness, especially when he has LESS ARMOR then Caitlyn. But their DPS shouldn't be high, we don't need season 2 all over again when champions built full tank and outDPSed damage based classes in the game. That isn't balanced. No, Nautilus shouldn't get more damage, because he would just force out the other junglers like Maokai forced out the other tops, yes, his anchor swing and animations in general should LOOK more powerful, especially after we saw them in the cinematic. But when people constantly whine that "Oh, this champion utterly removes these champions from the game." I find it incredibly stupid when they ask for another champion to do the same, because that is all that is going to happen if Nautilus gets more damage.