| The problem I see is that the first role of the method book is to teach the positions and the way logical fingerings are derived. All of the exercises in a method are written for that sole purpose and presented in a logical manner. For example, after extensive exercises in half and first positions, there are exercises that get the student shifting between the two. Sure they could be more musical sounding, but would they serve the purpose as well? There are a lot of funky intervals (eg. descending half steps) in Simandl that you won't usually find in music. But they are there to develop the left hand.
If you can find something in the orchestral rep. that is in only half and first positions, would it serve the purpose as well as the established methods?
I once had a similar thought to your's but in terms of etudes. There are a lot of orchestral excerpts that can serve as great exercises. But I don't think they could ever completely surplant etudes because etudes are written specifically to address certain problems. If you set out to work on Nanny Etude of Virtuosity #3, you're going to work on nothing but crazy-ass, diabolical arpeggios, no fluff or sugar coating. But for as diabolical as it is, that is something you're building for general application. Then you can use these general skills to help solve the specific problems encountered in real music.
I think if real music is used as the sole means for building technique, your technique will have more gaps. And besides, if either of our ideas would actually work, it probably would have been done already by some long-time orchestra professional and pedagogue who knows all of the repetoire inside and out. | 
