The United States made the biggest mistake decommissioning the Iowa Class Battleship. The cannons are great for shore bombardment, something that is needed if marines are to be deployed. They can provide support if a unit calls in a fire mission and can fire a variety of munitions. That being said, they should be modernized and equipped with more state of the art equipment, but we should not discontinue the battleship.
The days of "the bigger the better" are in the past. It's all about computer technology these days. The Iowa-class's greatest strength was its 16" gun turrets, which are essentially obsolete in the days of satellite-guided cruise missiles. The smaller guided-missile destroyers are the Navy's mainstays now. An Arleigh-Burke class ship could easily defeat an Iowa-class. Add to that the fact that you'd have to train tens of thousands of sailors on how to operate the old equipment, AND the cost of rehabbing the ships to combat status, and you end up with an extremely high cost that could be better spent elsewhere, such as electronic warfare platforms, new drone designs, etc. Spend that money on the future, not the past.
There are many problems with recommissioning the ship.
1. A BB cost as much to operate as an aircraft carrier
2. The cannons are obsolete, they are only good for a range of 23 miles and are vulnerable targets for cruise missiles. While they may be good if the battle involved line of sight, ships engage in battles far from any line of sight.
3. It can only hold 32 Tomahawk Cruise missiles, a DD, cheaper to operate, can hold 60.
That being said - it had a good history and was a great ship. It should stay that way.