Why InDesign is Better for Wireframing than Illustrator

UPDATE: I have put a PDF howto for wireframing in InDesign here:
Wireframing Using InDesign

Since April 2008 I have been working part time as peer coach to Interaction Design students here at the HRO. For next year’s program I am developing a wireframe workshop, since this is something that is lacking severely at our course. Having done my first internship at LBi Lost Boys I was introduced to InDesign as a tool for making wireframes. Since then I have relied on InDesign for almost all my wireframing needs and it has served me very well. However, I am aware that InDesign might not be such a widely used tool within the Interaction Design community and it was therefor decided to use Illustrator for the wireframing workshop. Having now worked in both these packages, here are my thoughts on why I prefer InDesign to Illustrator.

Pages
First and foremost, pagination. Interaction Design documents tend to be large, especially those for big platforms. Being able to have Word-like pages makes it a lot easier to organise your frames. Illustrator lacks this functionality, in this sense it is much more like Photoshop. You are forced to paste your wireframes into an InDesign document after creation.

One Package
This issue refers partly to the pagination problem. Essentially, you are using the same functionality in Illustrator to draw the wireframes than in InDesign. It is possible to draw all you need right within Indesign but it is impossible to make a proper document Indesign-style in Illustrator. This means that you are using two applications in stead of one to get the same job done.

Styles
Illustrator isn’t as good with paragraph styles, compared to InDesign. Although it is possible to define paragraph styles in Illustrator, it simply is not as robust as InDesign. I have the feeling that paragraph styles are an afterthought in Illustrations, whereas in InDesign it forms a major part of the functionality. Then there is also the fact that it is impossible to underline text in Illustrator, something that is vital.
EDIT: as Eric pointed out in the comments, it is actually possible to underline in Illustrator. Thanks!

Masters
Masters are a powerful tool in InDesign. It allows you to create templates that repeat themselves throughout your entire site. Indicating where the fold is, for instance, can be done on a master page. Recurring elements such as a header can be designed and placed in a master and simply applied when needed.

General Document Design
Using and knowing InDesign teaches basic document design skills, but more importantly, it teaches typography and like Information Architects Japan, I am a firm believer that Web Design is 95% Typography.

So, to conclude: Whilst Illustrator is a far more advanced illustration tool (as the name suggest) than InDesign, the drawing functionality found in InDesign is more than sufficient to develop high quality wireframes.