I don’t know what anyone means by ‘it’s hard to find proper fitting dropped nosebands today’. Good fitting ones are available.
A dropped noseband is more severe because it sits perpendicular to the line of the face. A flash sits at an angle to the face, so is always less severe.
Drop nosebands are usually recommended for horses that pull and ‘bull’ through the aids. It may be just what is needed. Or it may not be.
We on the bulletin board seem to react to ‘it’s more severe’ with moral outrage as if no piece of equipment we would ever use would or could be severe. But people need bits, cavesons and other equipment that is more or less severe to accomodate different situations.
We should always attempt to use the mildest equipment that keeps us safe and gets the job done, and we should always try to use technique vs more severe equipment, of course, but different types of bits and cavesons are definitely still needed. In fact I’d far rather change cavesons and keep with a medium bit than go to a more severe bit.
The flash does not ‘lower when it is loosened’ if it is fitted correctly.
The flash’s angle is determined by the caveson, and the caveson should be adjusted to fit fairly high on the horse’s face and kept snug. The flash can be loosened without loosening the caveson, keeping it at more of an angle to the face.
Another advantage of the flash is it makes a better bridge to riding with a plain caveson in the double bridle. Yes, I know some people here think that’s not true. But it is what I was taught and it is one more reason why flashes are used a lot.