You have to prove you qualify for SSDI/SSI. If you choose not to participate in the process you may severely limit your chances of approval. If you choose to attend, you can certainly try and keep your answers concise, of course.

If you want to limit your interaction with the judge, you'll need representation and you'll want to discuss why you'd prefer to limit your testimony as much as possible.

Personally, I can't imagine why you wouldn't want to take full advantage of a new opportunity to prove you should qualify for SSDI, (worst case scenario you can always appeal again) but apparently some people choose to waive their rights and this link explains those scenarios: http://www.ssa.gov/OP_Home/hallex/I-02/I-2-1-45.html