[wpm]

If the goal is to optimize the singular task of "get water off hands ASAP", sure it probably solves that fairly well.

There might be more to the task though. What affect does it have on the user? Getting splashed with water, usually at crotch height, is a nuisance and is somewhat embarassing. The loudness of these dryers is also a nuisance, and can be downright painful depending on how many are going at the same time in a large public bathroom. Long enough for permanent damage? Probably not for the average hand-washer, but for the people who have to clean those restrooms all day, perhaps an occupational hazard.

Also, the trough shaped ones are disgusting.

[justinrubek]

The trough ones are such a poor design. Carefully try to wiggle your fingers in there, and then they blow with force such that you touch the wet dirty surface that everyone else has touched. I don't understand why these things exist, let alone why people choose to put them in a bathroom.