Conclusion
To sum up, centered alignments are weak, but not bad. There’s a very important distinction there that you really must grasp to be a good designer. “Weak” implies that they can easily be taken too far and are easy to abuse. However, you can and should be using centered alignments in your designs.
Make sure that, if your entire layout is built on a centered alignment, you have a very simple design with only a few items. Once you start adding big blocks of text and lots of images, the centered alignments starts looking messy. Also, try building a solid left, justified or even right alignment for your page as a whole, then experiment with selectively dropping in centered alignments in key areas such as headlines. Finally, as a quick trick when you’re in a jam, try wrapping center-aligned portions in a box that goes with the flow of the rest of the page.