There are many reasons while the Coca-Cola bottle has changed over time. It’s not because science suggested the newer bottles to be better than the older ones. It’s simply because they know people can get tired of something they have gotten used to over time.
A redesigned blog sparks up interest, even without a new feature. Goal.com did that sometime last year and it was a huge success. There are also advantages to re-designing since better technologies are developed every day. But besides implementing the latest technologies, no blog should look the same way after about 3 years. That doesn’t make sense.
The only bloggers who can be excused from this redesign are those locked in the world of blogger. It seems technology is leaving them behind, and don’t be surprised if Google develops a new solution to make Blogger match up with WordPress.
For WordPress users, a redesign is as simple as purchasing a new theme and installing. Some themes might require customization though. Remember to keep a backup before doing this.