Hate to correct you but I work for the company that build HK Disney land so I have both been there and am pretty familiar with the park/material.
Second, while short, its not a 20 second ride. Under a minute sure, but not 20 seconds.
Third for the younger kids who I have seen ride it, I don't know any of them that are complaining about it not being a legacy attraction, that won't stand the test of time. Its a fun short ride, if you don't think its worth your time, don't get in line. If most people don't think it's worth their time, the market flush it out too.
But not every ride needs to be a long drawn out thing. Would it be better if it was a little longer, maybe. But comparing it to other kiddie coasters, Goofy Barnstormer is around 50sec or so, and Flight of the Hippogriff is about the same. I am not going to get all worked up and crazed about the missing 20-30 seconds.