This is very true, but an Iowa has seven and a half inches of deck armor and a foot-thick armor belt. An Exocet or Harpoon isn't gonna do much more than scratch the paint on that. And before anyone asks, yes a Shipwreck or something like that will take out damn near anything, but how many nations have such missiles? I think the better reason against the Iowas is size and whether something smaller can do the same job, as they are monstrous things to be sure.
No, you are repeating navy PR myths. Yes the numbers quote are right, but not the conclusion. Issues:
1) The main armor belt is near the water line. It is made of Class B armor (unhardened). For missiles attacks, it provides no protection. They come in above the belt, so the belt does not matter. And once the unused rocket fuel starts to burn, they create issues. If the 16" belt has fire on it, the steel will lose strength. The great weight will make the ship more likely to sink (break in half). And the damage can't be repaired. Even a handful of smaller missiles can result in permanent mission kill. i.e. you take to drydock and scrap.
2) The smaller missiles you list will penetrate the armor on kinetic energy alone. The all also can fit shape charged warheads. They can also be programmed to change final attack angles. In short, the penetrate.
3) The 7.5 inch armor you list is misleading. First, it is built on "all or nothing protection scheme". So large portions of the ship is unarmored. Second, that is max thickness. The armor is carefully thinned to provide just enough protection from enemy battleships. The weather deck is under 2", maybe under an 1". Now yes, this is hardened (Class A) armor, but it is not that impressive. Almost all modern tanks and other armored vehicles have the equivalent of a lot more than 7" of steel armor. Basically any anti-tank weapon known to god will penetrate the Iowa armor. What makes an Iowa tougher than a tank is that most of the Iowa is non-critical spaces. So the Iowa can take many Exocet hits, but eventually they will either find a critical space (catastrophic loss of ship) or they will start doing cumulative structural damage to the strength decks giving you a permanent mission kill. Yes, the Iowa likely takes a hit from one or two Exocets and keeps on the mission, but as the number climbs up towards 20 or so hits, the ship is a loss.
4) Plunging fire. The Iowa armor does provide some protection from land based artillery (if you are thinking of it as a Monitor), but is vulnerable to plunging (high angle) fire. Even a plan old 155mm artillery round is likely to breach the weather deck. Now without the fires associated with missiles, these are much, much less likely to greatly harm the ship.
5) The Iowa is horrible against any modern torpedo. How many nations have torpedoes? And if they have no submarines, exactly why do you need a Iowa to defeat say Chile?
I dearly love Battleships, but the USN is just misleading people on a lot of this stuff. The Iowa only had three roles. The main was to give Reagan good PR. They do make nice Monitors, and if kept in reserve status and we assume a 3-6 month leadup to a minor war, they do make nice support for the Marines. They may even be cost effective in this role. Third, they were big ships that could hold lots of modern missiles. They made an ok stop gap measure. The 16" guns have low value in modern naval war. Probably as likely to sink the Iowa in ammo explosion as actually take out an enemy warship that could not simply be sunk easier by shooting a missile. The armor is a negative. It makes it slower and more vulnerable to fire damage.