I don't really see a problem with this. Less experienced developers should be working on less interesting work/bug fixes, so the experienced developers can concentrate on the rest.

I'm an experienced developer and when I change jobs, I'm always given this type of work in the beginning. Bug fixes are great for learning a new application because you often times get to touch multiple parts of the application and gain experience from it.

On most teams, you need to earn your position as a developer that can handle some of these larger tasks.