They really can be a problem solver when people find flat bars too limiting or pain inducing and when the lower position of drop bars isn't wanted or needed.

Will be installing trekking bars on my new tandem as the wide hand position makes things very stable and as I will have two little stokers this will be very nice and will be able to have a position that puts my hands where the hoods on my drop bars normally sit.

If I spend too much time in a really low drop position it aggravates my back but being able to stretch out a little further and move forward and back instead of up and down is a good thing and you can get just as aero on trekking bars as you can when you ride with your hands on the hoods.

The stoker bars will probably be trekking bars too due to their versatility in positioning and excellent vibration damping qualities.