Before you answer let me paint a picture for you. Say you are designing a site for a client. The client wants lot’s of interactivity in the site, the sort of features that JQuery
So I have a product in the works. The product is a WordPress Plugin for managing Taxonomies and managing the taxonomies you have on posts. As I wanted to implement progressive enhancement within the UI of this plugin I started off the design thinking that I would add on the JQuery layer simply to make the UI a bit more interactive, as the final stage in the project.
However as I came to the end of the project I found that I had gone down a route which stopped me from implementing the features that I originally wanted to add. And I found that the user experience was not as pleasant as I had hoped for. The functionality was the same, but the experience was not as good as it could have been.