Dumbfounded

So, I don't really consider myself much of a TV watcher, but I'm not really a TV abstainer either (although I'd like to be). When I do watch the Ol' Tube, I'm usually watching the news, The History Channel, The Discovery Channel, The National Geographic Channel...you get the idea. So lately I've seen several shows about people who spend lots of money and effort to "bring up" ships and airplanes that have sunk or crashed and burned respectively to the bottom of the ocean/sea/lake. My question is , "Why?" These transport vehicles are at the bottom of the sea because they failed to do what they were intended to do. In other words, they suck. So now that they've been on the bottom of the sea for several decades, I'm guessing they suck even worse. What gets really crazy is that it costs more money to get the cruddy hunk of metal off the bottom of the ocean than it would cost to buy a brand new one that works!!! Brilliant. Then, once you've retrieved said sorry hunk of metal, it costs even more to "restore" it to its former suckiness. Now don't get me wrong, I understand that some of these boats and planes have historical value, but they (museums, collectors, the military, etc.) already have the same kinds of boats and planes (some still in service) that actually work. Why do they want to spend all that money to fish up the ones that didn't? I'm absolutely dumbfounded. Can someone explain this?