My thoughts are mixed on your question. I think noise or drag would be something to consider if fishing a pond or lake containing trout because a pond or lake would normally be deeper and have more "color" to the water. In deeper or "colored" water, the noise/drag may be something a person needs in their flies to attract the attention of a trout that is in deeper water or water that is not usually crystal clear. In most quality streams the water is shallow and very clear. An insect floating on the surface will be seen by the trout and it must float identical to the "real" insect. If it starts to "drag", this is seen by the trout as not being a natural drift that they have seen many times before and this causes them to be wary of what it is or is not. So, I feel that if the real insect usually puts up a lot of noise on the surface, like a grasshopper or cicada, when it lands on the water, this would be seen by the trout as being natural and they would eat it. If the real insect just floats along with no noise or drag, then your imitation needs no noise or drag or it may cause the trout to be wary of it. I have watched trout trying to attack damsel flies as they flitter above the water and there is no noise or drag attracting the trout, but, it is brought to the trout's attention by being seen from clear shallow water.

So, I feel that if the "food" you are trying to imitate usually makes a lot of noise or trashing on the water, then your fly needs the same noise or thrashing. If the natural does not make noise or drag, then your imitation needs none because it is seen and not heard by the trout. I honestly feel a trout feeds mostly by food that looks alive and not by noise or drag. My definition of "looks alive" would be a fly that has movements of the fly material that would represent the "legs" moving in the water or gills filtering water.

These are just my thoughts on this as far as trout are concerned. Now bass, muskie, pike and other larger species which are use to eating much larger food than insects, my thoughts would be different.