What you are referring to is commonly known as the "French Column". I suppose it shouldn't be surprising that English movies and the English version of Wikipedia are pretty dismissive of it. After all, that was the opinion of everyone's favorite English General, Wellington. And he was certainly able to back it up.
The first thing you have to realize is that Napoleonic-era unit tactics were not all about math. Getting the maximum possible fire on your opponent is important, but it isn't the only factor.
The greatest goal is to remove the enemy units from action. Now a unit (regiment, battalion, etc) obviously can be removed from action without killing every single person in that unit. How bad do you have to hurt them? That depends on oodles of factors (eg: training, experience, casualties, etc) that are often wound up into a big ball called "morale".
So a lot of Napoleanic-era tactics that may not make a lot of sense mathematically make a lot of sense when you factor in morale. For instance, the volley. Mathematically you'd be better off letting every man fire as fast as he possibly can, rather than making them all wait on a signal. However, there's a huge difference to the opposing unit whether your buddies around you are dying in dribs and drabs here and there, or in great big groups all at once. Volleys hit like a hammer rather than a steady rain.
The idea behind a French Column isn't to pour a lot of fire into the opposing unit. Instead, it is to concentrate the entire efforts of your unit into a small area (usually in the middle) of the enemy unit. The folks in the rest of the enemy unit may feel safer, but anyone at the point of impact looking at an entire French Column 50 or so men wide and hundreds deep making a beeline straight at their part of the line has a pretty good idea they are gonna die. A sensible human being (aka: all but the incredibly well-trained) looking at that will do whatever they can to get out of the way.
If you can break the enemy line there, you break their unit in two. If you then keep coming, you will suddenly have your whole unit in the middle of theirs, able to fire on all of them effectively in a line while they have found themselves in a column (assuming they don't just rout). The key to being able to do this is training and speed, and early on nobody could match Napoleon in these two qualities. It was almost like a Calvary charge for him, but done with infantry.
Here's a passage taken from a fan of the formation in Eric Flint's 1824: The Arkansas War (a work of alternative history):
The term "column" was a misnomer, he now realized, applied to the
fighting formation of the French armies of the Revolution. This bore
no resemblance at all to a long, slender line of men marching down a
It was more like a sledgehammer. Or perhaps a very blunt spear. Fifty
men across, at the front, firing as they came, with the rest of the
regiment in close support. The formation relied on speed and impact,
more like a cavalry charge than anything else Sam could think of.
Watching it in action, he could now understand why the formation had
eventually been abandoned. Very well trained and disciplined
professional armies, formed into lines, could bring too much fire to
bear on the front of the column. Hundreds of men against fifty.
But that presupposed the sort of professional armies trained and led
by generals like the Duke of Wellington...