I disagree. Having more information is always a good thing. Many times you may not know the best thing to put as a keyword. You get 100 characters to work with and that isn't a lot. I could come up with much more than that for all of my apps. If I had a better idea what people were searching for to find my apps I'd have a better idea of what best reflects the parts of my app people care about.
They should put the keywords that best reflects what their app is and does and leave it at that. In fact Apple should make it even harder to change.