"Is learning theory important? Should we, as pianists, solely focus on the artistry side of playing, or should we do written work (such as writing scales, cadences, learning harmony and counterpoint)? "
Well, the pianists have to do all such work you wrote about: they should focus theirs attention on the artistry side of playing and do the "written work" (such as writing scales, cadences, learning harmony and counterpoint). And much, much more! Of course, if they seriously like to possess the real knowledge of many various aspects of history, culture and arts of the mankind.
- Still, such acquiring cannot be organized INSTEAD of practicing the real artistry...
Look at the poetry: to create the poem one do not must be a professor of the literature, just inversely - professors never write good poems! We can be sure - to create any Artwork one cannot focus ones attention on peripheral things, as these all "writing works" are for the pianists. Because, "to create", must mean - "to synthesize". And the synthesizing, as a process, possesses totally different character as the analyzing. Artistic synthesizing, the creation, must be trained as particularly special TECHNIQUE, even if in the question is playing the piano in its very primarily phases there.
To achieve the mastery level in such technique, I am afraid, "learning theory", "do written work such as writing scales, cadences, learning harmony and counterpoint", etc - would NOT be enough. These all things are only the separate elements that even if taken together and enriched by many additional piano skills (as scales and arpeggios, octaves, chords, etc.) CANNOT form the artistic technique of the piano in its best. They have to be used as THE Great HELP, indeed; still they actually represent a DIFFERENT operational CATEGORY of our work.
The harmony can help to find the proper chord, yes - but unfortunately the harmony as a subject cannot explain: how such accurate chord has to be articulated on the piano to bring the expected artistic result?
The bad samples
Mechanical practicing of fingers and Dreaming about possibility to play scales & arpeggios Fast, Fast and even Faster - takes away any possibility to play truly fast. It is because such thinking puts the problem of tempo at the central point of the whole matter! Unfortunately the tempo as a problem depends NOT ONLY on mechanical abilities of fingers and CANNOT be solve through any purely mechanical tricks! As well solfeggio, harmony, counterpoint, etc - without any vivid interest toward the Beauty and its TECHNOLOGY, must bring only mournful, disintegrative results.
Having concrete OBJECT (VALUE, QUALITY of the SOUND) one will be able to raise the quality of ones artistic piano technique up to the levels of real mastery.
Only having the idea about the ways in which one can connect the artistic fantasy, creative (anticipative) hearing and the corporal elements into one well-organized entirety, one will be able to achieve the higher degrees in technique of the piano, absolutely.
The factual piano technique of master's degree is much complicated, many-sided and subtle, as commonly the piano adepts are able to imagine. And because there exists no possibility to achieve The Higher - through practicing The Lower, the pianists' IMAGINATION should be equipped with truly effective thinking and hearing skills. I mean, the students should be informed about some special values of the piano sound that HAVE TO BE WATCHED when practicing the instrument.
It has to be realized especially when training scales, arpeggios, etc - to change such habitually brainless work into artistically enjoyable, truly interesting activity. In our disposal there exist yet many psycho-techniques that can be used to upgrade all the technical skills we are speaking about:
- The image of the proper dynamic Zone of the sound
- The virtual bow that helps to integrate the hand's entirety
- An active vision of the sound, etc.
And what is truly interesting here: if student's attention would be even partially transferred from persistent mechanical readjustment of the fingers' action onto checking up the sounding results' quality - the whole upgrading process will go much faster.
It will very quickly come to light, that the physical powers' output is much bigger then the real needs. Economizing it, by hearing, the pianist will get remarkably big energetic balance that liberates the muscles and enlarges possibility to play FASTER & Faster & Faster!
Yes, just using the "Ears & Comp" all the values the pianists are so exceedingly waiting for (scales, arpeggios, octaves and chords in real tempo) would be definitely achieved. There is no other way round!
The ears, hearing, fantasy, artistic idea - all these components must be fully employed in every minute when pianist polishes his/her instrumental technique. It would be truly sorrowful if instead of them (ears, fantasy, artistic idea) one starts to use such gadgets as lego blocks or other accessories that focus pupils' attention on the peripheral matters. The practice of that kind, maybe, could be useful as help at theoretical subjects - using lego-blocks the teacher can SHOW HOW some musical pieces are built. Such supplementary gadgets belong yet once again to ANALYTICS; they cannot help to SHAPE the CREATION, that needs in much more special skills then the pure ANALYZE. They can help to UNDERSTAND the work and/or the process, still not to CREATE the Artwork.
I am quite sure, that even mentally retarded children might grown much better musically up if instead of use of lego blocks & others similar devices, the teacher will try to wake up theirs fantasy just using clearly metaphoric language, comparing musical happenings to everyday events, giving understandable musical samples, etc.
At the end I would like to emphasize one time again: these all things you were asked about, are in my opinion indisputably necessary in the piano studies. However, I am deeply afraid that you believe too strongly in theirs power: "to analyze something" does not mean, "to create something". Therefore they all who truly want to possess a technique of the piano in its higher denotation - they have to turn their attention toward such piano solution, which could provide them with necessary musical knowledge and skills of the master's level. The address is for me very sure: this is The Chopin's Method! Chopin's Method (developed by Prof. Neuhaus) is the sole and one formula that entirely shows how "the artistry side of playing" has to be used even in upgrading such technical skills, which - if one would like to use another methods - must be defined as truly brainless work...