There are a lot of good reasons why wordpress hosting is better than most other forms of blog scripts that are used for blogging. But to sum it all up, its mainly because people just find it much easier to work with, and thats for a lot of good reasons as well.
For instance, because WordPress is open source, its very popular and familiar to most webmasters, who have probably tried maintaining blogs in the past. So in case you will move to a new host or create a new website, you wont have to start from scratch with WordPress web hosting because you know your way around the blog.
Furthermore, the fact that its open source means that you have a rich resource of online support for this hosting. If you have problems, you can easily Google the solution up and lots of people will give useful tips that may help you out. Everyones trying to improve it, so they certainly wont hesitate to respond to your troubles.