Iron Man 3: Why Tony Stark destroyed his suits.

(SPOILER ALERT from here out for Iron Man 3)

Robert Downey Jr. as Tony Stark/Iron Man

Iron Man 3 came out on DVD, Blu-ray and every other digital whichever this week, rocketing from theaters into people's homes and movie collections. While there were some elements of the film that were controversial to fans, the largest of those was based in interpretation of the source material. One other, the destruction of Tony Stark's amassed army of Iron Man armors (which some refer to as 'The Iron Legion') along with the removal of the shrapnel from his heart, made some fans wonder how he could be Iron Man any longer, lacking both his chest-embedded power source and the suits it powered. Despite fan criticism, and personal uncertainty, I would posit that the destruction was not just a silly means to a Merry-Christmas-Pepper-fireworks-display, but something that was very much in character and a predictable move for Tony Stark. 

Tony Stark (RDJ) left,  facing down his other Iron Man suit

All throughout the Iron Man films, since his change of heart during a visit to a cave in Afghanistan, Tony 

Stark has been about peace through force, or at least disarmament of those to whom he and his company had played merchant of death. Faced with terrorists who use weapons his company sold them, Tony examines the moral conundrum that likely lies within all cases of arms sales: are my guns killing people? In response, he turns from using his mechanical genius for weapon construction to making a super-suit to defend those who couldn't defend themselves. The greatest problem with this is that Tony Stark as Iron Man has basically turned himself into a weapon in order to rid the world of weapons. There is always the possibility that someone else, someone less heroic that Tony, might also gain and use an Iron Man suit. While his friend Col. Rhodes does gain the use of one of his suits and takes on the name "War Machine," Rhodes is a friend, and a hero like Tony (he's certainly more responsible). However, that spreading of Iron Man technology is just a small part of the story. 

Hammer Industry Drones from Iron Man 2

Obadiah Stane in his version of the Iron Man armor

Ivan Vanko in his Whiplash armor

One of the main conflicts of Iron Man 2 is the attempts by Hammer Industries to duplicate the Iron Man technology. While their efforts fail to do exactly that, they do succeed in creating a drone army based upon Tony Stark's armor designs. Stark is faced with what he wanted to avoid: a weapons technology based on his work. His peace keeping defender is under threat of being turned into an inhuman army of technological killers.  

 Hammer Industries is ultimately thwarted and their drones are destroyed, partially due to their use in the vengeful plots of Ivan Vanko, but they are not the only reproductions of Tony Stark's Iron Man armor. In the first film, Tony Stark's greedy former friend and mentor Obadiah Stane creates his own, gargantuan, slightly flawed, version of Tony's armor. Also, following the failure of the Hammer drones to kill Tony, Ivan Vanko reveals his own armored suit based on Iron Man. Both are eventually destroyed in crippling combat with Iron Man (and for the latter, also War Machine), but the threat that someone will use Iron Man's technology for evil still exists, and is shown to be very real.
In Iron Man 3, the anonymity of the Iron Man suit is taken advantage of as War Machine, renamed Iron Patriot for PR reasons, is taken captive and his suit is used for nefarious schemes. Hidden behind the mask of a hero, villains are able to get into secure places and use the technology to their own evil ends. More people use Iron Man suits for evil and twist Tony's designs to create something that can face down evil and warring aggressors. It is in this context that the destruction of his Iron Man armors makes sense.

While the destruction of Tony's many suits in the end of the film show his release of fear, his need to be in control and security based upon his creations, it does go well with earlier character development. In the wake of the Avengers, Tony Stark retreats in fear to building an Iron Man army, coping and releasing energy by tinkering and constructing.

Stark's Legion of Iron Man armors in Iron Man 3

He builds up the army, a series of different suits, to try to personally counter what he sees as  overwhelming and unknown threats that might be looming in the future. This coping though has turned him once again into an arms manufacturer, in an arms race against time when the next alien invasion or whatever might happen. To stay true to his quest for peace (not a good Superman movie BTW), Iron Man must destroy his suits. He still has his computer with the designs and things that builds them in crazy quick time, so it would be a mistake to assume that Tony Stark is now armorless. but he does destroy his arsenal. He has to, because a build up of Iron Man suits plays right into the underlying conflict in all the Iron Man movies: the proliferation of the Iron Man technology might (and does) lead to the wrong people getting their hands on Tony's technology. The destruction of his suits allows Tony to move on from his crippling and damaging insecurities as well as continue his mission towards disarmament.