Far too often, I've heard some poet claim that they never want to have to do old, stodgy, formalized poetic styles. They claim that trying to do that old poetry is restrictive and is not what real poetry is about. I usually claim that they are pretentious little turds who just claim to be poets so they won't seem so pathetic.
There are plenty of good reasons for doing the old style, structured poetry. One of the best is that, when well executed, it can be quite beautiful. I'll illustrate the other main reason for doing it through analogy.
You cannot live in the United States for too long without encountering American football. It is a pervasive part of our culture. If you watch a game, you will never see the players go onto the field, put metal plates onto a metal bar, and then lift and lower the bar repeatedly. That just is not part of playing a game football. However, every football player lifts weights regularly. They go into a special room, put large metal plates on a metal bar, and then lift and lower the bar repeatedly even though that is never a part of game play.
Why would they spend all that time lifting and lowering a weighted bar that has nothing to do with the game they play? That's a bit obvious; it makes them stronger so they are better equipped to play the game.
By analogy then, why do we still do the old, stodgy, structured poetry? Simple, it makes us stronger as poets. It flexes our poetic muscles so we are better equipped to do our modern, less structured poetry. It makes us faster on our feet when we have to find the right word. It gives us better command of meter. It makes us work out. Then, when we must engage in the game of poetry, and it is just a game, we are better players.
You can still call yourself a poet if you don't do the exercise. I will not say that you are not a poet. I may, however, call you amateurish. Worse yet, I may just call you a poet but always prepend the word "bad".
You gotta pick the right guy to do the job.
Go out now and vote for LibertyBob.