Different strokes for different folks...

Myself, I don't like short forms for training. I want all the applications that my teachers want to teach me in there, and I want to practice them all, a lot. Demonstrations or competitions are another thing, though. Then a shorter form comes in handy. At my school, though, you have to learn the long form first.

From the purely technical side, the expression of the principles through many different angles found in a long form has a distinct health benefit that more limited routines don't have. This is demonstrable.

From an entirely opinionated point of view - an opinion which is intended to be provocative to my students, at least - why should a beginner waste time learning a short routine that will just be abandoned for a long one down the line? That time has to spent anyway, and there is so much information to be covered by a serious student that it doesn't make sense to me to take baby steps. Learn the long form and get it over with.

Of course, CMC style is different, they don't teach a long form, so this doesn't apply to them, I am thinking more of Ch'en, Yang and Wu family style students.

If a student just can't learn it, if it is too difficult, I tell them that maybe they have to learn something else first. My primary goal, my responsibility to my teachers, is accurate high-level transmisson of the art. Not many martial arts are so transmitted by coddling the beginning students. I know what I had to go through to learn what I know and know well. To learn what I've learned they have to do the work! If they do, I can teach them. If they don't, well, they will inevitably be passed up by people who started after them and may start to wonder why. If they simply get mad at all the hard work that is expected and quit, there are still plenty of fluffy "health only" classes that they can go and be mystical in. Good riddance.