The men in the Light Brigade are just doing their job; they're soldiers and it's their duty to fight. That's the core of what makes them appealing and heroic, but it's also the thing that makes their deaths tragic. The Brigade doesn't need to go on a suicide mission and charge their enemies (some commander seems to have given a bad order), and the Brigade knows that, but they do it anyway. That's the code of a soldier, and it's definitely what Tennyson is celebrating here – the last word in loyalty, in living up to your promises.
By leaving out the names of the individual soldiers, Tennyson focuses our attention on what they accomplished as a group, and on their unity and strength.
The commanders are almost completely erased from this poem. This makes them seem irrelevant and foolish, and allows us to give all our attention to the brave men of the Light Brigade.