to me, sensuality does not represent objectivity. in fact, it would mean the opposite - going by feelings. these feelings may be able to be communicated by concrete means (as you said, technique, etc.) but if the spiritual elements of your personality affect your sensuality - then you do have an interdependence of the two in interpretation (as to what you are trying to say to an audience).i like beethoven because he was connected to nature. he would often take walks, refresh his mind, and combine the natural world to also the psychological one. even though there are frustrations vented in his music, he never lets them overcome him. to me, it's taking control of your life, and not letting your feelings rule totally. but, realizing we're part of a bigger plan. i like beethoven's musical 'struggle' (as he was having to deal with deafness- terrible for a musician) and he decided very matter of factly that as long as there was some good he could do - that he should not end his own life.musicians (sometimes partly psychotic as you mentioned) if they become too much into the 'sensuality/feelings' side - become irrational. people praise them for their music - but do little to help them gain perspective in their personal life. we are no lesser or greater than anyone else just because we play an instrumetn. being in tune with other artistic endeavors makes you realize how small of spectrum musical expression is - to the complete human expression. i guess there are the rare artists that need to be sort of sequestered to work well - but, it's not a natural tendency for people to isolate themselves totally from the world. even beethoven recognized this and at least made an effort to not cut himself off. perhaps being understood is the problem musicians have to deal with (especially within ones family). eccentricity. i don't think any famous musician that i know of (including liszt) let their feelings totally rule them. otherwise they would never get anything done. most were extremely disciplined, read a lot, contemplated all areas of arts/sciences, and were constantly modifying or expanding their comfort zone. feelings often do not allow you to expand your zone. that must mean, to me, that they were also highly objective and experimentative to the actual process of music making.
All this is basically the reason why piano playing could not have any scientific approach, formulas, or solutions (as being argued on the other thread) as the bottomline is piano playing is an art, not science, and to repeat, what separates arts from science is that the former is both objective and subjective while the latter is just objective. That's why I see artists more "gifted" than scientists - learning how to be objective and subjective at the same time and how to interplay in between them as if "to create your own kind of mixture" makes an artist truly a rare genius!