You're right, the Flash Catalyst Wireframe Components list is a subset of the Spark component set exposed in Flash Builder.
In Catalyst we expose special tooling, properties, and experience around each spark component.
It is definitely our intent moving forward to continue to expose more and more Spark components, but as opposed to Builder each component we add requires some special work around exposing the user experience of working with, creating and manipulating that component.
I absolutely encourage you to leverage the fxpl (library) workflows to create and import your own components (and share with other Catalyst friends online if you feel so inclined ).
In the meantime, if you have specific high priority component requests, we'd love all the feedback we can get. Feel free to post a list of a couple high priority components here, or post them to the ideas site so we can get other users voting for them: http://ideas.adobe.com/flashcatalyst
Thanks for posting!
Thanks for the answer and the ideas link, Tara! -FS