I have to use collapsible poles--because I'm a shortie, the length I need for hiking is shorter than what I need for my shelter! It's also great to be able to collapse the poles and tie them on my pack if I need one or both hands for scrambling.

Trekking poles do help considerably those of us with leg/knee/foot problems, and I strongly suspect that their use may help prevent overuse injuries in the healthy.

Since my shelter requires only one trekking pole, I still have one available for short excursions around camp, such as fetching water. I'm not sure I'd want a shelter requiring two poles for that reason. For dayhiking or other longer excursions, I use the first measure I described earlier--take out the pole and weigh the tent down with a rock or two so it won't blow open if the wind comes up.