I'm currently taking ABRSM Grade 1 Jazz and I shall give my reason why I took the Jazz route instead of the classical route.
I've met people who own grade 7-8 certificates before. They can do almost anything under the sun. Side reading , flying fingers syndrome etc , the kinda expectations you have for a grade 7-8 student. The thing is , if you give them a piece and tell them improvise on ONLY the bass clef , they get dumbfounded. I used to think highly of these students but I sort of neglected the improvising aspect of it. It's not to say that all classical pianist can't improvise , but I would say a high number of classical pianist who owns a grade 7 or 8 certificate
that I've met before can't improvise. I've seen it with my very own eyes before and it kinda freaked me out totally....
I don't wanna be a "slave" for music just by playing directly from scores but I want to have some form of "freedom" when playing music. With no strings attached....
But if you were to look at certain classical pieces , if by looking at the structure of it , it's very hard to improvise on the spot but rather if you were to improvise a particular bar of notes , I guess you have to do some theory work first before attempting where else in Jazz , they give you the bass clef and the entire trebleclef bar is your dance floor.
So is Jazz complicated? I would say to a certain extent YES because it requires you to know your chord structure and scales well. Chord structures include inversions , which notes form which chords etc. It is true that the ABRSM board states that a candidate should possess a grade 3 classical certificate first before attempting grade 1 jazz. The reason being , you need to know your sense of pulse , good technic , chord formations , touch and so much more.
But , Jazz IS NOT HARD....
Yes you may find it difficult initially because remember , the candidate was once a classcially tranined pianist. So obviously the technics employed in classical playing is completely different from the jazz point of view. So I guess , it takes quite some time for the candidate to get used to the technics employed in jazz.
In classical , you play scales in straight motion....
In jazz , you play modes in "Swing" motion which means that every alternate note of the scale is accented. Accented notes should not be "striked" but rather the accented note should be "connected" to give that "swing" feel....
Jazz is complicated yes BUT not difficult