Jørgen Jakob Friis
Just to elaborate: we are not supposed to 'invent' the techniques rather than we are suppose to assimilate what we pick up from different senseis, training partners, weapons training etc and adjust it to fit our personal circumstances. Our body frame, length of arms and legs, speed and lots of other issues play a vital role.
Instead of making our body fit aikido - I think we should adapt our aikido to fit our bodies and minds. In that way we end up not being carbon copies of our senseis but rather new permutations with unique blends of physical and mental ability combined with unique blends of experience and knowledge.
Yes, I think it is important to synthesize and adapt what we do based on alot of factors as you mention. In BJJ in order to get your black belt this is essential. We call it "developing your game".
That said, I caution against using it as an excuse to be lazy and not practice things we may not want to. In judo there are many throws I don't like and would never probably use, however, it would not excuse me from being able to teach them or know them. So, we have to keep this in mind. I think that there should be a separation between developing your style and personality within Martial Arts, and mastering the fundamentals of a curriculum.